Snap for 9847313 from 0630c2d6ffb02017172e6cae725834801c6dd690 to car-apps-release

Change-Id: Ib09c7faaf04f9c1e8cc782807cab998aec21a833

17 files changed, 771 insertions, 347 deletions

diff --git a/res/drawable/ic_queue_button.xml b/res/drawable/ic_queue_button.xml
index 389c266..5681ab9 100644
--- a/res/drawable/ic_queue_button.xml
+++ b/res/drawable/ic_queue_button.xml
@@ -14,6 +14,7 @@
   See the License for the specific language governing permissions and
   limitations under the License.
 -->
+<!-- Deprecated resource. -->
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
     <item android:drawable="@drawable/selectable_button_background"
           android:height="@dimen/queue_button_background_size"
diff --git a/res/layout-port/metadata_normal.xml b/res/layout-port/metadata_normal.xml
index 65ee652..e2aecbb 100644
--- a/res/layout-port/metadata_normal.xml
+++ b/res/layout-port/metadata_normal.xml
@@ -48,31 +48,35 @@
         app:layout_constraintBottom_toTopOf="@+id/album_title"
         app:layout_constraintVertical_chainStyle="packed"/>
 
-    <TextView
+    <com.android.car.apps.common.TappableTextView
         android:id="@+id/artist"
-        android:layout_width="0dp"
+        android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:gravity="center"
         android:textAlignment="center"
         android:layout_marginTop="@dimen/metadata_title_subtitle_margin"
-        style="@style/MetadataPlaybackSubtitleStyle"
+        app:tappableTextStyle="@style/MetadataPlaybackSubtitleClickableStyle"
+        app:normalTextStyle="@style/MetadataPlaybackSubtitleStyle"
+        app:hideViewMode="gone"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintTop_toBottomOf="@id/title"
         app:layout_constraintBottom_toTopOf="@+id/album_title"/>
 
 
-    <TextView
+    <com.android.car.apps.common.TappableTextView
         android:id="@+id/album_title"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginTop="@dimen/metadata_subtitles_margin"
-        style="@style/MetadataPlaybackSubtitleStyle"
+        app:tappableTextStyle="@style/MetadataPlaybackSubtitleClickableStyle"
+        app:normalTextStyle="@style/MetadataPlaybackSubtitleStyle"
+        app:hideViewMode="gone"
         app:layout_goneMarginTop="@dimen/metadata_title_subtitle_margin"
         app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintEnd_toStartOf="@+id/progress_text_container"
+        app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintTop_toBottomOf="@id/artist"
-        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintBottom_toTopOf="@id/progress_text_container"
         app:layout_constraintHorizontal_chainStyle="packed"
         app:layout_constrainedWidth="true"/>
 
@@ -80,10 +84,11 @@
         android:id="@+id/progress_text_container"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        app:layout_constraintStart_toEndOf="@+id/album_title"
+        android:layout_marginTop="@dimen/metadata_subtitles_margin"
+        app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintEnd_toEndOf="parent"
-        app:layout_constraintTop_toTopOf="@+id/album_title"
-        app:layout_constraintBottom_toBottomOf="@+id/album_title"
+        app:layout_constraintTop_toBottomOf="@id/album_title"
+        app:layout_constraintBottom_toBottomOf="parent"
         layout="@layout/time_progress_text"/>
 
 </androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/res/layout/metadata_normal.xml b/res/layout/metadata_normal.xml
index f5df6ed..bc6dfc9 100644
--- a/res/layout/metadata_normal.xml
+++ b/res/layout/metadata_normal.xml
@@ -44,40 +44,40 @@
         app:layout_constraintBottom_toTopOf="@+id/artist"
         app:layout_constraintVertical_chainStyle="packed"/>
 
-    <TextView
+    <com.android.car.apps.common.TappableTextView
         android:id="@+id/artist"
-        android:layout_width="0dp"
+        android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginTop="@dimen/metadata_title_subtitle_margin"
-        style="@style/MetadataPlaybackSubtitleStyle"
+        app:tappableTextStyle="@style/MetadataPlaybackSubtitleClickableStyle"
+        app:normalTextStyle="@style/MetadataPlaybackSubtitleStyle"
+        app:hideViewMode="gone"
         app:layout_constraintStart_toStartOf="@id/title"
-        app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintTop_toBottomOf="@id/title"
         app:layout_constraintBottom_toTopOf="@+id/album_title"/>
 
-    <TextView
+    <com.android.car.apps.common.TappableTextView
         android:id="@+id/album_title"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginTop="@dimen/metadata_subtitles_margin"
-        style="@style/MetadataPlaybackSubtitleStyle"
+        app:tappableTextStyle="@style/MetadataPlaybackSubtitleClickableStyle"
+        app:normalTextStyle="@style/MetadataPlaybackSubtitleStyle"
+        app:hideViewMode="gone"
         app:layout_goneMarginTop="@dimen/metadata_title_subtitle_margin"
         app:layout_constraintStart_toStartOf="@id/title"
-        app:layout_constraintEnd_toStartOf="@+id/progress_text_container"
         app:layout_constraintTop_toBottomOf="@id/artist"
-        app:layout_constraintBottom_toBottomOf="@id/album_art"
-        app:layout_constraintHorizontal_chainStyle="packed"
-        app:layout_constraintHorizontal_bias="0.0"
+        app:layout_constraintBottom_toTopOf="@id/progress_text_container"
         app:layout_constrainedWidth="true"/>
 
     <include
         android:id="@+id/progress_text_container"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        app:layout_constraintStart_toEndOf="@+id/album_title"
-        app:layout_constraintEnd_toEndOf="parent"
-        app:layout_constraintTop_toTopOf="@+id/album_title"
-        app:layout_constraintBottom_toBottomOf="@+id/album_title"
+        android:layout_marginTop="@dimen/metadata_subtitles_margin"
+        app:layout_constraintStart_toStartOf="@id/title"
+        app:layout_constraintTop_toBottomOf="@+id/album_title"
+        app:layout_constraintBottom_toBottomOf="@id/album_art"
         layout="@layout/time_progress_text"/>
 
 </androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/res/layout/time_progress_text.xml b/res/layout/time_progress_text.xml
index a359994..053e262 100644
--- a/res/layout/time_progress_text.xml
+++ b/res/layout/time_progress_text.xml
@@ -20,6 +20,7 @@
     android:layout_width="wrap_content"
     android:layout_height="wrap_content">
 
+    <!-- For overlays where the time needs to be separated from other content, revive this view.
     <TextView
         android:id="@+id/outer_separator"
         android:layout_width="wrap_content"
@@ -27,6 +28,7 @@
         android:text="@string/dash_separator"
         style="@style/MetadataPlaybackSubtitleStyle"
     />
+    -->
 
     <TextView
         android:id="@+id/current_time"
diff --git a/res/values/id.xml b/res/values/id.xml
index c9d5250..341ec12 100644
--- a/res/values/id.xml
+++ b/res/values/id.xml
@@ -2,4 +2,5 @@
 <resources>
   <item type="id" name="imageDownloadTask"/>
   <item type="id" name="playback_seek_bar_container"/>
+  <item type="id" name="outer_separator"/>
 </resources>
diff --git a/res/values/overlayable.xml b/res/values/overlayable.xml
index 211e368..a950a0d 100644
--- a/res/values/overlayable.xml
+++ b/res/values/overlayable.xml
@@ -105,6 +105,11 @@ REGENERATE USING packages/apps/Car/tests/tools/rro/generate-overlayable.py
       <item type="id" name="item_container"/>
       <item type="id" name="max_time"/>
       <item type="id" name="media_activity_root"/>
+      <item type="id" name="menu_item_equalizer"/>
+      <item type="id" name="menu_item_search"/>
+      <item type="id" name="menu_item_selector"/>
+      <item type="id" name="menu_item_selector_with_source_logo"/>
+      <item type="id" name="menu_item_setting"/>
       <item type="id" name="metadata_container"/>
       <item type="id" name="minimized_playback_controls"/>
       <item type="id" name="now_playing_icon"/>
@@ -116,13 +121,13 @@ REGENERATE USING packages/apps/Car/tests/tools/rro/generate-overlayable.py
       <item type="id" name="playback_seek_bar_container"/>
       <item type="id" name="progress_text_container"/>
       <item type="id" name="queue_container"/>
+      <item type="id" name="queue_fragment_container"/>
       <item type="id" name="queue_list"/>
       <item type="id" name="queue_list_bottom_constraint"/>
       <item type="id" name="queue_list_item_subtitle"/>
       <item type="id" name="queue_list_item_title"/>
       <item type="id" name="queue_list_item_titles_container"/>
       <item type="id" name="queue_list_top_constraint"/>
-      <item type="id" name="queue_fragment_container"/>
       <item type="id" name="right_arrow"/>
       <item type="id" name="separator"/>
       <item type="id" name="spacer"/>
@@ -196,6 +201,7 @@ REGENERATE USING packages/apps/Car/tests/tools/rro/generate-overlayable.py
       <item type="style" name="MediaIconContainerStyle"/>
       <item type="style" name="MediaTintableIconContainerStyle"/>
       <item type="style" name="MetadataContainerStyle"/>
+      <item type="style" name="MetadataPlaybackSubtitleClickableStyle"/>
       <item type="style" name="MetadataPlaybackSubtitleStyle"/>
       <item type="style" name="MetadataPlaybackTitleStyle"/>
       <item type="style" name="QueueListItemSubtitleStyle"/>
diff --git a/res/values/styles.xml b/res/values/styles.xml
index 9d4682a..ab45e81 100644
--- a/res/values/styles.xml
+++ b/res/values/styles.xml
@@ -34,6 +34,9 @@
         <item name="android:includeFontPadding">false</item>
     </style>
 
+    <style name="MetadataPlaybackSubtitleClickableStyle" parent="MetadataPlaybackSubtitleStyle">
+    </style>
+
     <style name="MetadataContainerStyle">
         <item name="android:layout_width">match_parent</item>
         <item name="android:layout_height">wrap_content</item>
diff --git a/res/xml/menuitems_playback.xml b/res/xml/menuitems_playback.xml
index d7284b5..1a4305e 100644
--- a/res/xml/menuitems_playback.xml
+++ b/res/xml/menuitems_playback.xml
@@ -18,7 +18,7 @@
     xmlns:app="http://schemas.android.com/apk/res-auto">
     <MenuItem
         app:id="@+id/menu_item_queue"
-        app:carUiIcon="@drawable/ic_queue_button"
+        app:carUiIcon="@drawable/ic_tracklist"
         app:activatable="true"/>
     <MenuItem
         app:id="@+id/menu_item_selector_with_source_logo"
diff --git a/src/com/android/car/media/BrowseStack.java b/src/com/android/car/media/BrowseStack.java
new file mode 100644
index 0000000..b235b6f
--- /dev/null
+++ b/src/com/android/car/media/BrowseStack.java
@@ -0,0 +1,264 @@
+/*
+ * Copyright 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.car.media;
+
+
+import android.support.v4.media.MediaBrowserCompat;
+import android.util.Log;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.android.car.media.common.MediaItemMetadata;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Stack;
+import java.util.function.Predicate;
+
+/**
+ * The Browse stack maintains a history of the various media items the user has been exploring, so
+ * that some navigation steps can easily be undone.
+ *
+ * A new entry is pushed onto the stack when the user selects one of the visible items.
+ *
+ * Each entry in the stack is decorated with a {@link BrowseEntryType}. The types are grouped into
+ * three categories that identify the origin of the media items:
+ *   - TREE:   the {@link MediaBrowserCompat}'s root.
+ *   - SEARCH: a search query
+ *   - LINK:   a linked item
+ * Note that media apps decide whether searched and linked items are also part of the browse tree.
+ *
+ * The fist element of the stack must be a {@link BrowseEntryType#TREE_ROOT} and be the only one of
+ * that type. If the stack contains a {@link BrowseEntryType#TREE_TAB}, it must be the second
+ * element (call {@link #insertRootTab} to add it).
+ */
+public class BrowseStack {
+
+    private static final String TAG = "BrowseStack";
+
+    public enum BrowseEntryType {
+        /** The {@link MediaBrowserCompat}'s root. */
+        TREE_ROOT,
+        /** The currently selected tab (one of the children of the root). */
+        TREE_TAB,
+        /** A descendant of the currently selected tab. */
+        TREE_BROWSE,
+        /** The list of search results. */
+        SEARCH_RESULTS,
+        /** An item descending from one of the search results. */
+        SEARCH_BROWSE,
+        /** An item that was linked to, regardless of the modality (NPV or Browse action). */
+        LINK,
+        /** An item descending from a linked entry. */
+        LINK_BROWSE;
+
+        BrowseEntryType getNextEntryBrowseType() {
+            switch (this) {
+                case TREE_ROOT:
+                    Log.e(TAG, "getNextEntryBrowseType should not be called on the root");
+                    // fallthrough
+                case TREE_TAB:
+                case TREE_BROWSE:
+                    return TREE_BROWSE;
+                case SEARCH_RESULTS:
+                case SEARCH_BROWSE:
+                    return SEARCH_BROWSE;
+                case LINK:
+                case LINK_BROWSE:
+                    return LINK_BROWSE;
+                default:
+                    Log.e(TAG, "getNextEntryBrowseType doesn't know about: " + this);
+                    return TREE_BROWSE;
+            }
+        }
+    }
+
+    /**
+     * Records the key elements of a stack entry:
+     *    - {@link BrowseEntryType} its type
+     *    - {@link MediaItemMetadata}
+     *        + null for {@link BrowseEntryType#TREE_ROOT} | @link BrowseEntryType#SEARCH_RESULTS}.
+     *        + otherwise non null, the item displayed at this level of the stack
+     *    - {@link BrowseViewController} the controller in charge of this level. Note that
+     *        controllers must be destroyed and recreated on UI configuration changes.
+     */
+    static class BrowseEntry {
+        final BrowseEntryType mType;
+        @Nullable final MediaItemMetadata mItem;
+        private @Nullable BrowseViewController mController;
+
+        private BrowseEntry(@NonNull BrowseEntryType type, @Nullable MediaItemMetadata item,
+                @NonNull BrowseViewController controller) {
+            mType = type;
+            mItem = item;
+            mController = controller;
+        }
+
+        @Nullable BrowseViewController getController() {
+            return mController;
+        }
+
+        void destroyController() {
+            if (mController != null) {
+                mController.destroy();
+                mController = null;
+            }
+        }
+
+        void setRecreatedController(@NonNull BrowseViewController controller) {
+            mController = controller;
+        }
+    }
+
+    private final Stack<BrowseEntry> mEntries = new Stack<>();
+
+    BrowseStack() {
+    }
+
+    /** Returns the number of entries in the stack. */
+    int size() {
+        return mEntries.size();
+    }
+
+    void pushRoot(@NonNull BrowseViewController controller) {
+        if (mEntries.isEmpty()) {
+            mEntries.push(new BrowseEntry(BrowseEntryType.TREE_ROOT, null, controller));
+        } else {
+            Log.e(TAG, "Ignoring pushRoot on a non empty stack.");
+        }
+    }
+
+    void pushSearchResults(@NonNull BrowseViewController controller) {
+        mEntries.push(new BrowseEntry(BrowseEntryType.SEARCH_RESULTS, null, controller));
+    }
+
+    void pushEntry(@NonNull BrowseEntryType type, @NonNull MediaItemMetadata item,
+            @NonNull BrowseViewController controller) {
+        mEntries.push(new BrowseEntry(type, item, controller));
+    }
+
+    /** Inserts a tab at the start of the stack. */
+    void insertRootTab(@NonNull MediaItemMetadata item, @NonNull BrowseViewController ctrl) {
+        if (mEntries.isEmpty() || (BrowseEntryType.TREE_ROOT != mEntries.get(0).mType)) {
+            Log.e(TAG, "insertRootTab must be called AFTER adding a root.");
+        } else {
+            mEntries.insertElementAt(new BrowseEntry(BrowseEntryType.TREE_TAB, item, ctrl), 1);
+        }
+    }
+
+    @Nullable
+    BrowseEntry peek() {
+        return mEntries.isEmpty() ? null : mEntries.peek();
+    }
+
+    BrowseEntry pop() {
+        return mEntries.pop();
+    }
+
+    /** Returns the current controller being displayed. */
+    @Nullable
+    BrowseViewController getCurrentController() {
+        return mEntries.isEmpty() ? null : mEntries.peek().mController;
+    }
+
+    /** Returns the {@link BrowseEntryType} of the entry at the top of the stack. */
+    @Nullable
+    BrowseEntryType getCurrentEntryType() {
+        return mEntries.isEmpty() ? null : mEntries.peek().mType;
+    }
+
+    /** Returns the current item being displayed. */
+    @Nullable
+    MediaItemMetadata getCurrentMediaItem() {
+        return mEntries.isEmpty() ? null : mEntries.peek().mItem;
+    }
+
+    boolean isShowingSearchResults() {
+        return (getCurrentEntryType() == BrowseEntryType.SEARCH_RESULTS);
+    }
+
+    List<BrowseEntry> getEntries() {
+        return Collections.unmodifiableList(mEntries);
+    }
+
+    List<BrowseEntry> removeAllEntriesExceptRoot() {
+        List<BrowseEntry> result = new ArrayList<>(mEntries.size());
+        List<BrowseEntry> sublist = mEntries.subList(1, mEntries.size());
+        result.addAll(sublist);
+        sublist.clear();
+        return result;
+    }
+
+    List<BrowseEntry> removeTreeEntriesExceptRoot() {
+        return removeEntries(entry -> (entry.mType == BrowseEntryType.TREE_TAB
+                || entry.mType == BrowseEntryType.TREE_BROWSE));
+    }
+
+    List<BrowseEntry> removeSearchEntries() {
+        return removeEntries(entry -> (entry.mType == BrowseEntryType.SEARCH_RESULTS
+                || entry.mType == BrowseEntryType.SEARCH_BROWSE));
+    }
+
+    List<BrowseEntry> removeObsoleteEntries(@NonNull BrowseViewController controller,
+            @NonNull Collection<MediaItemMetadata> removedChildren) {
+        List<BrowseEntry> result = new ArrayList<>();
+        int ctrlIndex = -1;
+        BrowseEntryType typeToRemove = null;
+        for (int index = 0; index < mEntries.size(); index++) {
+            if (controller == mEntries.get(index).mController) {
+                ctrlIndex = index;
+                typeToRemove = mEntries.get(index).mType.getNextEntryBrowseType();
+                break;
+            }
+        }
+
+        if (ctrlIndex < 0 || ctrlIndex >= mEntries.size() - 1) {
+            // Controller not found or it has no child in the stack.
+            return result;
+        }
+
+        final int firstChild = ctrlIndex + 1;
+        if (removedChildren.contains(mEntries.get(firstChild).mItem)) {
+            int endRange = ctrlIndex + 2;
+            while (endRange < mEntries.size() && mEntries.get(endRange).mType == typeToRemove) {
+                endRange++;
+            }
+            List<BrowseEntry> sublist = mEntries.subList(firstChild, endRange);
+            result.addAll(sublist);
+            sublist.clear();
+        }
+        return result;
+    }
+
+    private List<BrowseEntry> removeEntries(@NonNull Predicate<BrowseEntry> shouldRemove) {
+        List<BrowseEntry> result = new ArrayList<>(mEntries.size());
+        Stack<BrowseEntry> kept = new Stack<>();
+        for (BrowseEntry entry: mEntries) {
+            if (shouldRemove.test(entry)) {
+                result.add(entry);
+            } else {
+                kept.push(entry);
+            }
+        }
+        mEntries.clear();
+        mEntries.addAll(kept);
+        return result;
+    }
+}
diff --git a/src/com/android/car/media/BrowseViewController.java b/src/com/android/car/media/BrowseViewController.java
index 43f97c0..175064d 100644
--- a/src/com/android/car/media/BrowseViewController.java
+++ b/src/com/android/car/media/BrowseViewController.java
@@ -45,7 +45,6 @@ import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.core.util.Pair;
 import androidx.fragment.app.FragmentActivity;
-import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.Observer;
 import androidx.lifecycle.ViewModelProviders;
 import androidx.recyclerview.widget.RecyclerView;
@@ -136,7 +135,7 @@ public class BrowseViewController {
 
         @Override
         protected void onBrowsableItemClicked(@NonNull MediaItemMetadata item) {
-            mCallbacks.onBrowsableItemClicked(item);
+            mCallbacks.goToMediaItem(item);
         }
 
         @Override
@@ -209,8 +208,8 @@ public class BrowseViewController {
          */
         void onPlayableItemClicked(@NonNull MediaItemMetadata item);
 
-        /** Invoked when the user clicks on a browsable item. */
-        void onBrowsableItemClicked(@NonNull MediaItemMetadata item);
+        /** Displays the given item. It may not be a child of the current node. */
+        void goToMediaItem(@NonNull MediaItemMetadata item);
 
         /** Invoked when user clicks on the mini playback bar in an empty browse
          *
@@ -249,24 +248,19 @@ public class BrowseViewController {
             Callbacks callbacks,
             ViewGroup container,
             @NonNull MediaItemMetadata parentItem,
-            MediaItemsLiveData mediaItems,
             MediaItemsRepository mediaRepo,
-            MutableLiveData<Map<String, CustomBrowseAction>> globalBrowseActions,
             int rootBrowsableHint,
             int rootPlayableHint) {
-        return new BrowseViewController(callbacks, container, parentItem, mediaItems,
-                rootBrowsableHint, rootPlayableHint, mediaRepo, globalBrowseActions, true);
+        return new BrowseViewController(callbacks, container, parentItem,
+                mediaRepo.getMediaChildren(parentItem.getId()), rootBrowsableHint, rootPlayableHint,
+                mediaRepo, true);
     }
 
     /** Creates a controller to display the top results of a search query (in a list). */
     static BrowseViewController newSearchResultsController(
-            Callbacks callbacks,
-            ViewGroup container,
-            MediaItemsLiveData mediaItems,
-            MediaItemsRepository mediaRepo,
-            MutableLiveData<Map<String, CustomBrowseAction>> globalBrowseActions) {
-        return new BrowseViewController(
-                callbacks, container, null, mediaItems, 0, 0, mediaRepo, globalBrowseActions, true);
+            Callbacks callbacks, ViewGroup container, MediaItemsRepository mediaRepo) {
+        return new BrowseViewController(callbacks, container, null, mediaRepo.getSearchMediaItems(),
+                0, 0, mediaRepo, true);
     }
 
     /**
@@ -277,11 +271,9 @@ public class BrowseViewController {
     static BrowseViewController newRootController(
             Callbacks callbacks,
             ViewGroup container,
-            MediaItemsLiveData mediaItems,
-            MediaItemsRepository mediaRepo,
-            MutableLiveData<Map<String, CustomBrowseAction>> globalBrowseActions) {
-        return new BrowseViewController(callbacks, container, null, mediaItems, 0, 0, mediaRepo,
-                globalBrowseActions, false);
+            MediaItemsRepository mediaRepo) {
+        return new BrowseViewController(callbacks, container, null, mediaRepo.getRootMediaItems(),
+                0, 0, mediaRepo, false);
     }
 
     /**
@@ -337,7 +329,6 @@ public class BrowseViewController {
             int rootBrowsableHint,
             int rootPlayableHint,
             MediaItemsRepository mediaRepo,
-            MutableLiveData<Map<String, CustomBrowseAction>> globalBrowseActions,
             boolean displayMediaItems) {
         mCallbacks = callbacks;
         mParentItem = parentItem;
@@ -412,7 +403,7 @@ public class BrowseViewController {
         mUxrContentLimiter.setAdapter(mLimitedBrowseAdapter);
         activity.getLifecycle().addObserver(mUxrContentLimiter);
 
-        globalBrowseActions.observe(activity, actions -> {
+        mMediaRepo.getCustomBrowseActions().observe(activity, actions -> {
             mGlobalActions = actions;
             browseAdapter.setGlobalCustomActions(actions);
             configureCustomActionsHeader(actions, maxActions);
@@ -424,6 +415,15 @@ public class BrowseViewController {
         mMediaItems.observe(activity, mItemsObserver);
     }
 
+    /**
+     * Returns whether the children of the parentItem given to this controller have been loaded and
+     * the given item is one of them.
+     */
+    boolean hasChild(MediaItemMetadata item) {
+        List<MediaItemMetadata> children = FutureData.getData(mMediaItems.getValue());
+        return (children != null) && (children.contains(item));
+    }
+
     private void initCustomActionsHeader(MediaItemMetadata parentItem, int maxActions) {
         if (parentItem == null || maxActions <= 0) {
             return;
@@ -526,7 +526,7 @@ public class BrowseViewController {
                         new BrowseActionCallback() {
                             @Override
                             public void onItemLoaded(MediaItem item) {
-                                mCallbacks.onBrowsableItemClicked(new MediaItemMetadata(item));
+                                mCallbacks.goToMediaItem(new MediaItemMetadata(item));
                             }
                         });
             }
@@ -591,10 +591,6 @@ public class BrowseViewController {
         }
     }
 
-    public MediaItemMetadata getParentItem() {
-        return mParentItem;
-    }
-
     /** Shares the browse adapter with the given view... #local-hack. */
     public void shareBrowseAdapterWith(RecyclerView view) {
         view.setAdapter(mLimitedBrowseAdapter);
diff --git a/src/com/android/car/media/MediaActivity.java b/src/com/android/car/media/MediaActivity.java
index d5c962a..eef8888 100644
--- a/src/com/android/car/media/MediaActivity.java
+++ b/src/com/android/car/media/MediaActivity.java
@@ -75,7 +75,6 @@ import com.android.car.ui.utils.CarUxRestrictionsUtil;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Objects;
-import java.util.Stack;
 
 /**
  * This activity controls the UI of media. It also updates the connection status for the media app
@@ -114,9 +113,6 @@ public class MediaActivity extends FragmentActivity implements MediaActivityCont
     private float mCloseVectorY;
     private float mCloseVectorNorm;
 
-    private final PlaybackFragment.PlaybackFragmentListener mPlaybackFragmentListener =
-            () -> changeMode(Mode.BROWSING);
-
     private MediaTrampolineHelper mMediaTrampoline;
 
     /**
@@ -133,7 +129,6 @@ public class MediaActivity extends FragmentActivity implements MediaActivityCont
         FATAL_ERROR
     }
 
-
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -160,10 +155,7 @@ public class MediaActivity extends FragmentActivity implements MediaActivityCont
         localViewModel.getBrowsedMediaSource().observe(this, this::onMediaSourceChanged);
 
         mMediaTrampoline = new MediaTrampolineHelper(this);
-
         mPlaybackFragment = new PlaybackFragment();
-        mPlaybackFragment.setListener(mPlaybackFragmentListener);
-
 
         Size maxArtSize = MediaAppConfig.getMediaItemsBitmapMaxSize(this);
         mMiniPlaybackControls = findViewById(R.id.minimized_playback_controls);
@@ -197,6 +189,7 @@ public class MediaActivity extends FragmentActivity implements MediaActivityCont
         mMediaActivityController = new MediaActivityController(this, getMediaItemsRepository(),
                 mCarPackageManager, mBrowseContainer);
 
+        mPlaybackFragment.setListener(mMediaActivityController.getPlaybackFragmentListener());
         mPlaybackContainer.setOnTouchListener(new ClosePlaybackDetector(this));
     }
 
@@ -268,7 +261,7 @@ public class MediaActivity extends FragmentActivity implements MediaActivityCont
             boolean isFatalError = false;
             if (!TextUtils.isEmpty(displayedMessage)) {
                 // If browse content -> not fatal
-                if (mMediaActivityController.browseTreeHasChildren()) {
+                if (mMediaActivityController.browseTreeHasChildrenList()) {
                     showToastOrDialog(displayedMessage, intent, label, mediaSource);
                 } else {
                     boolean isDistractionOptimized =
@@ -453,7 +446,8 @@ public class MediaActivity extends FragmentActivity implements MediaActivityCont
         }
     }
 
-    private void changeMode(Mode mode) {
+    @Override
+    public void changeMode(Mode mode) {
         if (mMode == mode) {
             if (Log.isLoggable(TAG, Log.INFO)) {
                 Log.i(TAG, "Mode " + mMode + " change is ignored");
@@ -463,6 +457,11 @@ public class MediaActivity extends FragmentActivity implements MediaActivityCont
         changeModeInternal(mode, true);
     }
 
+    @Override
+    public void changeSource(MediaSource source) {
+        mMediaTrampoline.setLaunchedMediaSource(source.getBrowseServiceComponentName());
+    }
+
     private void changeModeInternal(Mode mode, boolean hideViewAnimated) {
         if (Log.isLoggable(TAG, Log.INFO)) {
             Log.i(TAG, "Changing mode from: " + mMode + " to: " + mode);
@@ -616,12 +615,7 @@ public class MediaActivity extends FragmentActivity implements MediaActivityCont
 
         static class MediaServiceState {
             Mode mMode = Mode.BROWSING;
-            Stack<MediaItemMetadata> mBrowseStack = new Stack<>();
-            Stack<MediaItemMetadata> mSearchStack = new Stack<>();
-            /** True when the search bar has been opened or when the search results are browsed. */
-            boolean mSearching;
-            /** True iif the list of search results is being shown (implies mIsSearching). */
-            boolean mShowingSearchResults;
+            BrowseStack mBrowseStack = new BrowseStack();
             String mSearchQuery;
             boolean mQueueVisible = false;
             boolean mHasPlayableItem = false;
@@ -681,12 +675,6 @@ public class MediaActivity extends FragmentActivity implements MediaActivityCont
             return getSavedState().mMode;
         }
 
-        @Nullable
-        MediaItemMetadata getSelectedTab() {
-            Stack<MediaItemMetadata> stack = getSavedState().mBrowseStack;
-            return (stack != null && !stack.empty()) ? stack.firstElement() : null;
-        }
-
         void setQueueVisible(boolean visible) {
             getSavedState().mQueueVisible = visible;
         }
@@ -712,35 +700,14 @@ public class MediaActivity extends FragmentActivity implements MediaActivityCont
             return mBrowsedMediaSource;
         }
 
-        @NonNull Stack<MediaItemMetadata> getBrowseStack() {
+        @NonNull BrowseStack getBrowseStack() {
             return getSavedState().mBrowseStack;
         }
 
-        @NonNull Stack<MediaItemMetadata> getSearchStack() {
-            return getSavedState().mSearchStack;
-        }
-
-        /** Returns whether search mode is on (showing search results or browsing them). */
-        boolean isSearching() {
-            return getSavedState().mSearching;
-        }
-
-        boolean isShowingSearchResults() {
-            return getSavedState().mShowingSearchResults;
-        }
-
         String getSearchQuery() {
             return getSavedState().mSearchQuery;
         }
 
-        void setSearching(boolean isSearching) {
-            getSavedState().mSearching = isSearching;
-        }
-
-        void setShowingSearchResults(boolean isShowing) {
-            getSavedState().mShowingSearchResults = isShowing;
-        }
-
         void setSearchQuery(String searchQuery) {
             getSavedState().mSearchQuery = searchQuery;
         }
diff --git a/src/com/android/car/media/MediaActivityController.java b/src/com/android/car/media/MediaActivityController.java
index 63b512a..6875e4e 100644
--- a/src/com/android/car/media/MediaActivityController.java
+++ b/src/com/android/car/media/MediaActivityController.java
@@ -32,20 +32,19 @@ import android.view.inputmethod.InputMethodManager;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.fragment.app.FragmentActivity;
-import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.Observer;
 import androidx.lifecycle.ViewModelProviders;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 
 import com.android.car.apps.common.util.FutureData;
-import com.android.car.apps.common.util.ViewUtils;
 import com.android.car.apps.common.util.ViewUtils.ViewAnimEndListener;
-import com.android.car.media.common.CustomBrowseAction;
+import com.android.car.media.BrowseStack.BrowseEntryType;
+import com.android.car.media.MediaActivity.Mode;
+import com.android.car.media.PlaybackFragment.PlaybackFragmentListener;
 import com.android.car.media.common.MediaItemMetadata;
 import com.android.car.media.common.browse.MediaBrowserViewModelImpl;
 import com.android.car.media.common.browse.MediaItemsRepository;
-import com.android.car.media.common.browse.MediaItemsRepository.MediaItemsLiveData;
 import com.android.car.media.common.source.MediaBrowserConnector.BrowsingState;
 import com.android.car.media.common.source.MediaSource;
 import com.android.car.media.widgets.AppBarController;
@@ -62,7 +61,6 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
-import java.util.Stack;
 
 /**
  * Controls the views of the {@link MediaActivity}.
@@ -79,30 +77,21 @@ public class MediaActivityController extends ViewControllerBase {
     private Insets mCarUiInsets;
     private boolean mPlaybackControlsVisible;
 
-    private final Map<MediaItemMetadata, BrowseViewController> mBrowseViewControllersByNode =
-            new HashMap<>();
+    // Entries whose controller should be destroyed once their view is hidden.
+    private final Map<View, BrowseStack.BrowseEntry> mEntriesToDestroy = new HashMap<>();
 
-    // Controllers that should be destroyed once their view is hidden.
-    private final Map<View, BrowseViewController> mBrowseViewControllersToDestroy = new HashMap<>();
-
-    private final BrowseViewController mRootLoadingController;
-    private final BrowseViewController mSearchResultsController;
+    private final RecyclerView mToolbarSearchResultsView;
 
     /**
      * Stores the reference to {@link MediaActivity.ViewModel#getBrowseStack}.
      * Updated in {@link #onMediaSourceChanged}.
      */
-    private Stack<MediaItemMetadata> mBrowseStack;
-    /**
-     * Stores the reference to {@link MediaActivity.ViewModel#getSearchStack}.
-     * Updated in {@link #onMediaSourceChanged}.
-     */
-    private Stack<MediaItemMetadata> mSearchStack;
+    private BrowseStack mBrowseStack;
     private final MediaActivity.ViewModel mViewModel;
 
     private int mRootBrowsableHint;
     private int mRootPlayableHint;
-    private boolean mBrowseTreeHasChildren;
+    private boolean mBrowseTreeHasChildrenList;
     private boolean mAcceptTabSelection = true;
 
     /**
@@ -115,6 +104,8 @@ public class MediaActivityController extends ViewControllerBase {
     private final Observer<BrowsingState> mMediaBrowsingObserver =
             this::onMediaBrowsingStateChanged;
 
+    private final PlaybackFragment.PlaybackFragmentListener mPlaybackFragmentListener;
+
     /**
      * Callbacks (implemented by the hosting Activity)
      */
@@ -134,6 +125,16 @@ public class MediaActivityController extends ViewControllerBase {
 
         /** Returns the activity. */
         FragmentActivity getActivity();
+
+        /** Activates the given mode. */
+        void changeMode(Mode mode);
+
+        /** Switches to the given source. */
+        void changeSource(MediaSource source);
+    }
+
+    PlaybackFragmentListener getPlaybackFragmentListener() {
+        return mPlaybackFragmentListener;
     }
 
     /**
@@ -141,56 +142,53 @@ public class MediaActivityController extends ViewControllerBase {
      */
     private boolean navigateBack() {
         boolean result = false;
-        if (!isAtTopStack()) {
-            hideAndDestroyControllerForItem(getStack().pop());
+        if (isStacked()) {
+            hideAndDestroyStackEntry(mBrowseStack.pop());
 
             // Show the parent (if any)
             showCurrentNode(true);
 
-            if (isAtTopStack() && mViewModel.isSearching()) {
-                showSearchResults(true);
-            }
-
             updateAppBar();
             result = true;
         }
         return result;
     }
 
-    private void reopenSearch() {
-        clearStack(mSearchStack);
-        showSearchResults(true);
-        updateAppBar();
-    }
-
     private FragmentActivity getActivity() {
         return mCallbacks.getActivity();
     }
 
-    /** Returns the browse or search stack. */
-    private Stack<MediaItemMetadata> getStack() {
-        return mViewModel.isSearching() ? mSearchStack : mBrowseStack;
+    /** Returns true when at least one entry can be removed from the stack. */
+    private boolean isStacked() {
+        List<BrowseStack.BrowseEntry> entries = mBrowseStack.getEntries();
+        if (entries.size() <= 1) {
+            // The root can't be removed from the stack.
+            return false;
+        } else if (entries.get(1).mType == BrowseEntryType.TREE_TAB) {
+            // Tabs can't be removed from the stack
+            return entries.size() > 2;
+        }
+        return true;
     }
 
-    /**
-     * @return whether the user is at the top of the browsing stack.
-     */
-    private boolean isAtTopStack() {
-        if (mViewModel.isSearching()) {
-            return mSearchStack.isEmpty();
-        } else {
-            // The mBrowseStack stack includes the tab...
-            return mBrowseStack.size() <= 1;
+    @Nullable
+    private MediaItemMetadata getSelectedTab() {
+        List<BrowseStack.BrowseEntry> entries = mBrowseStack.getEntries();
+        if (2 <= entries.size() && entries.get(1).mType == BrowseEntryType.TREE_TAB) {
+            return entries.get(1).mItem;
         }
+        return null;
     }
 
+    /** Destroys controllers but should NOT change the stack for the source. */
     private void clearMediaSource() {
-        showSearchMode(false);
-        for (BrowseViewController controller : mBrowseViewControllersByNode.values()) {
-            controller.destroy();
+        for (BrowseStack.BrowseEntry entry : mBrowseStack.getEntries()) {
+            entry.destroyController();
+        }
+        mBrowseTreeHasChildrenList = false;
+        if (mToolbarSearchResultsView != null) {
+            mToolbarSearchResultsView.setAdapter(null);
         }
-        mBrowseViewControllersByNode.clear();
-        mBrowseTreeHasChildren = false;
     }
 
     private void updateSearchQuery(@Nullable String query) {
@@ -204,9 +202,6 @@ public class MediaActivityController extends ViewControllerBase {
     void onMediaSourceChanged(@Nullable MediaSource mediaSource) {
         super.onMediaSourceChanged(mediaSource);
 
-        updateTabs((mediaSource != null) ? null : new ArrayList<>());
-
-        mSearchStack = mViewModel.getSearchStack();
         mBrowseStack = mViewModel.getBrowseStack();
 
         updateAppBar();
@@ -227,6 +222,12 @@ public class MediaActivityController extends ViewControllerBase {
 
                 boolean canSearch = MediaBrowserViewModelImpl.getSupportsSearch(browser);
                 mAppBarController.setSearchSupported(canSearch);
+
+                if (mBrowseStack.size() <= 0) {
+                    mBrowseStack.pushRoot(BrowseViewController.newRootController(
+                            mBrowseCallbacks, mBrowseArea, mMediaItemsRepository));
+                }
+                showCurrentNode(true);
                 break;
 
             case DISCONNECTING:
@@ -249,55 +250,28 @@ public class MediaActivityController extends ViewControllerBase {
         mCallbacks = callbacks;
         mMediaItemsRepository = mediaItemsRepo;
         mViewModel = ViewModelProviders.of(activity).get(MediaActivity.ViewModel.class);
-        mSearchStack = mViewModel.getSearchStack();
         mBrowseStack = mViewModel.getBrowseStack();
         mBrowseArea = mContent.requireViewById(R.id.browse_content_area);
         mFpv = activity.requireViewById(R.id.fpv);
 
-        MediaItemsLiveData rootMediaItems = mediaItemsRepo.getRootMediaItems();
-        MutableLiveData<Map<String, CustomBrowseAction>> globalBrowseActions =
-                mediaItemsRepo.getCustomBrowseActions();
-        mRootLoadingController =
-                BrowseViewController.newRootController(
-                        mBrowseCallbacks,
-                        mBrowseArea,
-                        rootMediaItems,
-                        mediaItemsRepo,
-                        globalBrowseActions);
-        mRootLoadingController.getContent().setAlpha(1f);
-
-        mSearchResultsController =
-                BrowseViewController.newSearchResultsController(
-                        mBrowseCallbacks,
-                        mBrowseArea,
-                        mMediaItemsRepository.getSearchMediaItems(),
-                        mediaItemsRepo,
-                        globalBrowseActions);
-
-        boolean showingSearch = mViewModel.isShowingSearchResults();
-        ViewUtils.setVisible(mSearchResultsController.getContent(), showingSearch);
-        if (showingSearch) {
-            mSearchResultsController.getContent().setAlpha(1f);
-        }
-
         mAppBarController.setListener(mAppBarListener);
         mAppBarController.setSearchQuery(mViewModel.getSearchQuery());
         if (mAppBarController.getSearchCapabilities().canShowSearchResultsView()) {
-            // TODO(b/180441965) eliminate the need to create a different view and use
-            //     mSearchResultsController.getContent() instead.
-            RecyclerView toolbarSearchResultsView = new RecyclerView(activity);
-            mSearchResultsController.shareBrowseAdapterWith(toolbarSearchResultsView);
+            // TODO(b/180441965) eliminate the need to create a different view
+            mToolbarSearchResultsView = new RecyclerView(activity);
 
             ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(
                     ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
-            toolbarSearchResultsView.setLayoutParams(params);
-            toolbarSearchResultsView.setLayoutManager(new LinearLayoutManager(activity));
-            toolbarSearchResultsView.setBackground(
+            mToolbarSearchResultsView.setLayoutParams(params);
+            mToolbarSearchResultsView.setLayoutManager(new LinearLayoutManager(activity));
+            mToolbarSearchResultsView.setBackground(
                     activity.getDrawable(R.drawable.car_ui_ime_wide_screen_background));
 
             mAppBarController.setSearchConfig(SearchConfig.builder()
-                    .setSearchResultsView(toolbarSearchResultsView)
+                    .setSearchResultsView(mToolbarSearchResultsView)
                     .build());
+        } else {
+            mToolbarSearchResultsView = null;
         }
 
         updateAppBar();
@@ -309,20 +283,64 @@ public class MediaActivityController extends ViewControllerBase {
             onMediaSourceChanged(future.isLoading() ? null : future.getData());
         });
 
-        rootMediaItems.observe(activity, this::onRootMediaItemsUpdate);
+        mMediaItemsRepository.getRootMediaItems().observe(activity, this::onRootMediaItemsUpdate);
         mViewModel.getMiniControlsVisible().observe(activity, this::onPlaybackControlsChanged);
+
+        mPlaybackFragmentListener = (source, mediaItem) -> {
+            if (source == null || mediaItem == null) {
+                Log.e(TAG, "goToMediaItem error S: " + source + " MI: " + mediaItem);
+                return;
+            } else if (Log.isLoggable(TAG, Log.DEBUG)) {
+                Log.d(TAG, "goToMediaItem S: " + source + " MI: " + mediaItem);
+            }
+
+            mCallbacks.changeMode(Mode.BROWSING);
+
+            if (!Objects.equals(source, mViewModel.getMediaSourceValue())) {
+                mCallbacks.changeSource(source);
+            }
+
+            navigateTo(mediaItem);
+        };
+    }
+
+    private BrowseViewController recreateController(BrowseStack.BrowseEntry entry) {
+        switch (entry.mType) {
+            case TREE_ROOT:
+                return BrowseViewController.newRootController(
+                        mBrowseCallbacks, mBrowseArea, mMediaItemsRepository);
+            case SEARCH_RESULTS:
+                updateSearchQuery(mViewModel.getSearchQuery());
+                return BrowseViewController.newSearchResultsController(
+                        mBrowseCallbacks, mBrowseArea, mMediaItemsRepository);
+            default:
+                if (entry.mItem == null) {
+                    Log.e(TAG, "Can't recreate controller for a null item!");
+                    return null;
+                }
+                return BrowseViewController.newBrowseController(
+                        mBrowseCallbacks, mBrowseArea, entry.mItem,
+                        mMediaItemsRepository, mRootBrowsableHint, mRootPlayableHint);
+        }
     }
 
     void onDestroy() {
         mMediaItemsRepository.getBrowsingState().removeObserver(mMediaBrowsingObserver);
+        for (BrowseStack.BrowseEntry entry : mBrowseStack.getEntries()) {
+            entry.destroyController();
+        }
+        if (mToolbarSearchResultsView != null) {
+            mToolbarSearchResultsView.setAdapter(null);
+        }
     }
 
-    private AppBarController.AppBarListener mAppBarListener = new BasicAppBarListener() {
+    private final AppBarController.AppBarListener mAppBarListener = new BasicAppBarListener() {
         @Override
         public void onTabSelected(MediaItemMetadata item) {
-            if (mAcceptTabSelection && (item != null) && (item != mViewModel.getSelectedTab())) {
-                clearStack(mBrowseStack);
-                mBrowseStack.push(item);
+            if (mAcceptTabSelection && (item != null) && (item != getSelectedTab())) {
+                // Clear the entire stack, including search and links.
+                hideAndDestroyStackEntries(mBrowseStack.removeAllEntriesExceptRoot());
+                mBrowseStack.insertRootTab(item, createControllerForItem(item));
                 showCurrentNode(true);
                 updateAppBar();
             }
@@ -330,13 +348,7 @@ public class MediaActivityController extends ViewControllerBase {
 
         @Override
         public void onSearchSelection() {
-            if (mViewModel.isSearching()) {
-                reopenSearch();
-            } else {
-                showSearchMode(true);
-                updateAppBar();
-                mAppBarController.setSearchQuery(mViewModel.getSearchQuery());
-            }
+            showSearchResults();
         }
 
         @Override
@@ -358,15 +370,14 @@ public class MediaActivityController extends ViewControllerBase {
         }
 
         @Override
-        public void onBrowsableItemClicked(@NonNull MediaItemMetadata item) {
+        public void goToMediaItem(@NonNull MediaItemMetadata item) {
             hideKeyboard();
-            navigateInto(item);
+            navigateTo(item);
         }
 
         @Override
         public void onBrowseEmptyListPlayItemClicked() {
             mCallbacks.onBrowseEmptyListPlayItemClicked();
-
         }
 
         @Override
@@ -378,18 +389,12 @@ public class MediaActivityController extends ViewControllerBase {
         @Override
         public void onChildrenNodesRemoved(@NonNull BrowseViewController controller,
                 @NonNull Collection<MediaItemMetadata> removedNodes) {
-            if (mBrowseStack.contains(controller.getParentItem())) {
-                for (MediaItemMetadata node : removedNodes) {
-                    int indexOfNode = mBrowseStack.indexOf(node);
-                    if (indexOfNode >= 0) {
-                        clearStack(mBrowseStack.subList(indexOfNode, mBrowseStack.size()));
-                        if (!mViewModel.isShowingSearchResults()) {
-                            showCurrentNode(true);
-                            updateAppBar();
-                        }
-                        break; // The stack contains at most one of the removed nodes.
-                    }
-                }
+            List<BrowseStack.BrowseEntry> entries =
+                    mBrowseStack.removeObsoleteEntries(controller, removedNodes);
+            if (!entries.isEmpty()) {
+                hideAndDestroyStackEntries(entries);
+                showCurrentNode(true);
+                updateAppBar();
             }
         }
 
@@ -405,19 +410,14 @@ public class MediaActivityController extends ViewControllerBase {
     };
 
     private final ViewAnimEndListener mViewAnimEndListener = view -> {
-        BrowseViewController toDestroy = mBrowseViewControllersToDestroy.remove(view);
+        BrowseStack.BrowseEntry toDestroy = mEntriesToDestroy.remove(view);
         if (toDestroy != null) {
-            toDestroy.destroy();
+            toDestroy.destroyController();
         }
     };
 
     boolean onBackPressed() {
         boolean success = navigateBack();
-        if (!success && mViewModel.isSearching()) {
-            showSearchMode(false);
-            updateAppBar();
-            success = true;
-        }
         if (success) {
             // When the back button is pressed, if a CarUiRecyclerView shows up and it's in rotary
             // mode, restore focus in the CarUiRecyclerView.
@@ -426,18 +426,41 @@ public class MediaActivityController extends ViewControllerBase {
         return success;
     }
 
-    boolean browseTreeHasChildren() {
-        return mBrowseTreeHasChildren;
+    boolean browseTreeHasChildrenList() {
+        return mBrowseTreeHasChildrenList;
+    }
+
+    private BrowseEntryType getNextEntryType(@NonNull MediaItemMetadata item) {
+        BrowseViewController topController = mBrowseStack.getCurrentController();
+        if (topController == null) {
+            Log.e(TAG, "topController should not be null in getNextEntryType!!");
+            return BrowseEntryType.LINK;
+        }
+
+        if (topController.hasChild(item)) {
+            // If the item is a child of the top controller, treat this as a regular browse action
+            BrowseEntryType currentType = mBrowseStack.getCurrentEntryType();
+            if (currentType == null) {
+                Log.e(TAG, "mBrowseStack.getCurrentEntryType returned null !?!");
+                return BrowseEntryType.LINK;
+            }
+            return currentType.getNextEntryBrowseType();
+        }
+
+        return BrowseEntryType.LINK;
     }
 
-    private void navigateInto(@NonNull MediaItemMetadata item) {
-        showSearchResults(false);
+    private void navigateTo(@NonNull MediaItemMetadata item) {
+        if (Objects.equals(item, mBrowseStack.getCurrentMediaItem())) {
+            Log.i(TAG, "navigateInto item already shown");
+            return;
+        }
 
-        // Hide the current node (parent)
+        // Hide the current node (eg: parent)
         showCurrentNode(false);
 
         // Make item the current node
-        getStack().push(item);
+        mBrowseStack.pushEntry(getNextEntryType(item), item, createControllerForItem(item));
 
         // Show the current node (item)
         showCurrentNode(true);
@@ -446,40 +469,37 @@ public class MediaActivityController extends ViewControllerBase {
     }
 
     @NonNull
-    private BrowseViewController getControllerForItem(@NonNull MediaItemMetadata item) {
-        BrowseViewController controller = mBrowseViewControllersByNode.get(item);
-        MutableLiveData<Map<String, CustomBrowseAction>> globalBrowseActions =
-                mMediaItemsRepository.getCustomBrowseActions();
-        if (controller == null) {
-            controller =
-                    BrowseViewController.newBrowseController(
-                            mBrowseCallbacks,
-                            mBrowseArea,
-                            item,
-                            mMediaItemsRepository.getMediaChildren(item.getId()),
-                            mMediaItemsRepository,
-                            globalBrowseActions,
-                            mRootBrowsableHint,
-                            mRootPlayableHint);
-
-            if (mCarUiInsets != null) {
-                controller.onCarUiInsetsChanged(mCarUiInsets);
-            }
-            controller.onPlaybackControlsChanged(mPlaybackControlsVisible);
+    private BrowseViewController createControllerForItem(@NonNull MediaItemMetadata item) {
+        BrowseViewController controller =
+                BrowseViewController.newBrowseController(mBrowseCallbacks, mBrowseArea,
+                        item, mMediaItemsRepository, mRootBrowsableHint, mRootPlayableHint);
+        adjustBoundaries(controller);
+        return controller;
+    }
 
-            mBrowseViewControllersByNode.put(item, controller);
+    private void adjustBoundaries(@NonNull BrowseViewController controller) {
+        if (mCarUiInsets != null) {
+            controller.onCarUiInsetsChanged(mCarUiInsets);
         }
-        return controller;
+        controller.onPlaybackControlsChanged(mPlaybackControlsVisible);
     }
 
     private void showCurrentNode(boolean show) {
-        MediaItemMetadata currentNode = getCurrentMediaItem();
-        if (currentNode == null) {
+        BrowseStack.BrowseEntry entry = mBrowseStack.peek();
+        if (entry == null) {
+            Log.e(TAG, "Can't show a null entry!");
             return;
         }
-        // Only create a controller to show it.
-        BrowseViewController controller = show ? getControllerForItem(currentNode) :
-                mBrowseViewControllersByNode.get(currentNode);
+
+        BrowseViewController controller = entry.getController();
+        if (controller == null && show) {
+            // Controller was previously destroyed by a media source or UI config change, recreate.
+            controller = recreateController(entry);
+            if (controller != null) {
+                adjustBoundaries(controller);
+                entry.setRecreatedController(controller);
+            }
+        }
 
         if (controller != null) {
             showHideContentAnimated(show, controller.getContent(), mViewAnimEndListener);
@@ -491,14 +511,13 @@ public class MediaActivityController extends ViewControllerBase {
     // as the controller isn't ready to show the browse data of the new media source (it hasn't
     // connected to it (b/217159531).
     private void restoreFocusInCurrentNode() {
-        MediaItemMetadata currentNode = getCurrentMediaItem();
-        if (currentNode == null) {
+        BrowseViewController controller = mBrowseStack.getCurrentController();
+        if (controller == null) {
             return;
         }
-        BrowseViewController controller = getControllerForItem(currentNode);
         CarUiRecyclerView carUiRecyclerView =
                 controller.getContent().findViewById(R.id.browse_list);
-        if (carUiRecyclerView != null && carUiRecyclerView instanceof LazyLayoutView
+        if (carUiRecyclerView instanceof LazyLayoutView
                 && !carUiRecyclerView.getView().hasFocus()
                 && !carUiRecyclerView.getView().isInTouchMode()) {
             LazyLayoutView lazyLayoutView = (LazyLayoutView) carUiRecyclerView;
@@ -509,7 +528,7 @@ public class MediaActivityController extends ViewControllerBase {
     private void showHideContentAnimated(boolean show, @NonNull View content,
             @Nullable ViewAnimEndListener listener) {
         CarUiRecyclerView carUiRecyclerView = content.findViewById(R.id.browse_list);
-        if (carUiRecyclerView != null && carUiRecyclerView instanceof LazyLayoutView
+        if (carUiRecyclerView instanceof LazyLayoutView
                 && !carUiRecyclerView.getView().isInTouchMode()) {
             // If a CarUiRecyclerView is about to hide and it has focus, park the focus on the
             // FocusParkingView before hiding the CarUiRecyclerView. Otherwise hiding the focused
@@ -532,56 +551,46 @@ public class MediaActivityController extends ViewControllerBase {
         showHideViewAnimated(show, content, mFadeDuration, listener);
     }
 
+    private void showSearchResults() {
+        // Remove previous search entries from the stack (if any)
+        hideAndDestroyStackEntries(mBrowseStack.removeSearchEntries());
 
+        // Hide the current node
+        showCurrentNode(false);
 
-    private void showSearchResults(boolean show) {
-        if (mViewModel.isShowingSearchResults() != show) {
-            mViewModel.setShowingSearchResults(show);
-            showHideContentAnimated(show, mSearchResultsController.getContent(), null);
+        // Push a new search controller
+        BrowseViewController controller = BrowseViewController.newSearchResultsController(
+                mBrowseCallbacks, mBrowseArea, mMediaItemsRepository);
+        adjustBoundaries(controller);
+        if (mToolbarSearchResultsView != null) {
+            controller.shareBrowseAdapterWith(mToolbarSearchResultsView);
         }
-    }
+        mBrowseStack.pushSearchResults(controller);
 
-    private void showSearchMode(boolean show) {
-        if (mViewModel.isSearching() != show) {
-            if (show) {
-                showCurrentNode(false);
-            }
-
-            mViewModel.setSearching(show);
-            showSearchResults(show);
-
-            if (!show) {
-                showCurrentNode(true);
-            }
-        }
-    }
+        // Show the search controller
+        showCurrentNode(true);
 
-    /**
-     * @return the current item being displayed
-     */
-    @Nullable
-    private MediaItemMetadata getCurrentMediaItem() {
-        Stack<MediaItemMetadata> stack = getStack();
-        return stack.isEmpty() ? null : stack.lastElement();
+        updateAppBar();
+        mAppBarController.setSearchQuery(mViewModel.getSearchQuery());
     }
 
     @Override
     public void onCarUiInsetsChanged(@NonNull Insets insets) {
         mCarUiInsets = insets;
-        for (BrowseViewController controller : mBrowseViewControllersByNode.values()) {
-            controller.onCarUiInsetsChanged(mCarUiInsets);
+        for (BrowseStack.BrowseEntry entry : mBrowseStack.getEntries()) {
+            if (entry.getController() != null) {
+                entry.getController().onCarUiInsetsChanged(mCarUiInsets);
+            }
         }
-        mRootLoadingController.onCarUiInsetsChanged(mCarUiInsets);
-        mSearchResultsController.onCarUiInsetsChanged(mCarUiInsets);
     }
 
     void onPlaybackControlsChanged(boolean visible) {
         mPlaybackControlsVisible = visible;
-        for (BrowseViewController controller : mBrowseViewControllersByNode.values()) {
-            controller.onPlaybackControlsChanged(mPlaybackControlsVisible);
+        for (BrowseStack.BrowseEntry entry : mBrowseStack.getEntries()) {
+            if (entry.getController() != null) {
+                entry.getController().onPlaybackControlsChanged(mPlaybackControlsVisible);
+            }
         }
-        mRootLoadingController.onPlaybackControlsChanged(mPlaybackControlsVisible);
-        mSearchResultsController.onPlaybackControlsChanged(mPlaybackControlsVisible);
     }
 
     private void hideKeyboard() {
@@ -590,34 +599,32 @@ public class MediaActivityController extends ViewControllerBase {
         in.hideSoftInputFromWindow(mContent.getWindowToken(), 0);
     }
 
-    private void hideAndDestroyControllerForItem(@Nullable MediaItemMetadata item) {
-        if (item == null) {
-            return;
-        }
-        BrowseViewController controller = mBrowseViewControllersByNode.get(item);
+    private void hideAndDestroyStackEntry(@NonNull BrowseStack.BrowseEntry entry) {
+        BrowseViewController controller = entry.getController();
         if (controller == null) {
+            Log.e(TAG, "Controller already destroyed for: " + entry.mItem);
             return;
         }
-
         if (controller.getContent().getVisibility() == View.VISIBLE) {
             View view = controller.getContent();
-            mBrowseViewControllersToDestroy.put(view, controller);
+            mEntriesToDestroy.put(view, entry);
             showHideContentAnimated(false, view, mViewAnimEndListener);
         } else {
-            controller.destroy();
+            entry.destroyController();
+        }
+
+        if (mToolbarSearchResultsView != null && entry.mType == BrowseEntryType.SEARCH_RESULTS) {
+            mToolbarSearchResultsView.setAdapter(null);
         }
-        mBrowseViewControllersByNode.remove(item);
     }
 
     /**
-     * Clears the given stack (or a portion of a stack) and destroys the old controllers (after
-     * their view is hidden).
+     * Destroys the given stack entries (after their view is hidden).
      */
-    private void clearStack(List<MediaItemMetadata> stack) {
-        for (MediaItemMetadata item : stack) {
-            hideAndDestroyControllerForItem(item);
+    private void hideAndDestroyStackEntries(List<BrowseStack.BrowseEntry> entries) {
+        for (BrowseStack.BrowseEntry entry : entries) {
+            hideAndDestroyStackEntry(entry);
         }
-        stack.clear();
     }
 
     /**
@@ -643,13 +650,13 @@ public class MediaActivityController extends ViewControllerBase {
             mAppBarController.setActiveItem(null);
             if (items != null) {
                 // Only do this when not loading the tabs or we loose the saved one.
-                clearStack(mBrowseStack);
+                hideAndDestroyStackEntries(mBrowseStack.removeTreeEntriesExceptRoot());
             }
             updateAppBar();
             return;
         }
 
-        MediaItemMetadata oldTab = mViewModel.getSelectedTab();
+        MediaItemMetadata oldTab = getSelectedTab();
         MediaItemMetadata newTab = items.contains(oldTab) ? oldTab : items.get(0);
 
         try {
@@ -659,11 +666,11 @@ public class MediaActivityController extends ViewControllerBase {
 
             if (oldTab != newTab) {
                 // Tabs belong to the browse stack.
-                clearStack(mBrowseStack);
-                mBrowseStack.push(newTab);
+                hideAndDestroyStackEntries(mBrowseStack.removeTreeEntriesExceptRoot());
+                mBrowseStack.insertRootTab(newTab, createControllerForItem(newTab));
             }
 
-            if (!mViewModel.isShowingSearchResults()) {
+            if (mBrowseStack.size() <= 2) {
                 // Needed when coming back to an app after a config change or from another app,
                 // or when the tab actually changes.
                 showCurrentNode(true);
@@ -675,12 +682,10 @@ public class MediaActivityController extends ViewControllerBase {
     }
 
     private CharSequence getAppBarTitle() {
-        boolean isStacked = !isAtTopStack();
-
         final CharSequence title;
-        if (isStacked) {
+        if (isStacked()) {
             // If not at top level, show the current item as title
-            MediaItemMetadata item = getCurrentMediaItem();
+            MediaItemMetadata item = mBrowseStack.getCurrentMediaItem();
             title = item != null ? item.getTitle() : "";
         } else if (mTopItems == null) {
             // If still loading the tabs, force to show an empty bar.
@@ -701,17 +706,16 @@ public class MediaActivityController extends ViewControllerBase {
      * Update elements of the appbar that change depending on where we are in the browse.
      */
     private void updateAppBar() {
-        boolean isSearching = mViewModel.isSearching();
-        boolean isStacked = !isAtTopStack();
+        boolean isSearchMode = mBrowseStack.isShowingSearchResults();
+        boolean isStacked = isStacked();
         if (Log.isLoggable(TAG, Log.DEBUG)) {
             Log.d(TAG, "App bar is in stacked state: " + isStacked);
         }
 
-        mAppBarController.setSearchMode(isSearching ? SearchMode.SEARCH : SearchMode.DISABLED);
-        mAppBarController.setNavButtonMode(isStacked || isSearching
-                ? NavButtonMode.BACK : NavButtonMode.DISABLED);
-        mAppBarController.setTitle(!isSearching ? getAppBarTitle() : null);
-        mAppBarController.showSearchIfSupported(!isSearching || isStacked);
+        mAppBarController.setSearchMode(isSearchMode ? SearchMode.SEARCH : SearchMode.DISABLED);
+        mAppBarController.setNavButtonMode(isStacked ? NavButtonMode.BACK : NavButtonMode.DISABLED);
+        mAppBarController.setTitle(getAppBarTitle());
+        mAppBarController.showSearchIfSupported(!isSearchMode);
     }
 
     private void onRootMediaItemsUpdate(FutureData<List<MediaItemMetadata>> data) {
@@ -719,7 +723,7 @@ public class MediaActivityController extends ViewControllerBase {
             if (Log.isLoggable(TAG, Log.INFO)) {
                 Log.i(TAG, "Loading browse tree...");
             }
-            mBrowseTreeHasChildren = false;
+            mBrowseTreeHasChildrenList = false;
             updateTabs(null);
             return;
         }
@@ -727,12 +731,12 @@ public class MediaActivityController extends ViewControllerBase {
         List<MediaItemMetadata> items =
                 MediaBrowserViewModelImpl.filterItems(/*forRoot*/ true, data.getData());
 
-        boolean browseTreeHasChildren = items != null && !items.isEmpty();
+        boolean browseTreeHasChildrenList = items != null;
         if (Log.isLoggable(TAG, Log.INFO)) {
             Log.i(TAG, "Browse tree loaded, status (has children or not) changed: "
-                    + mBrowseTreeHasChildren + " -> " + browseTreeHasChildren);
+                    + mBrowseTreeHasChildrenList + " -> " + browseTreeHasChildrenList);
         }
-        mBrowseTreeHasChildren = browseTreeHasChildren;
+        mBrowseTreeHasChildrenList = browseTreeHasChildrenList;
         mCallbacks.onRootLoaded();
         updateTabs(items != null ? items : new ArrayList<>());
     }
diff --git a/src/com/android/car/media/PlaybackFragment.java b/src/com/android/car/media/PlaybackFragment.java
index 438f739..47d925f 100644
--- a/src/com/android/car/media/PlaybackFragment.java
+++ b/src/com/android/car/media/PlaybackFragment.java
@@ -48,7 +48,9 @@ import com.android.car.media.PlaybackQueueFragment.PlaybackQueueCallback;
 import com.android.car.media.common.MediaItemMetadata;
 import com.android.car.media.common.MetadataController;
 import com.android.car.media.common.PlaybackControlsActionBar;
+import com.android.car.media.common.browse.MediaItemsRepository;
 import com.android.car.media.common.playback.PlaybackViewModel;
+import com.android.car.media.common.source.MediaSource;
 import com.android.car.media.common.source.MediaSourceViewModel;
 import com.android.car.media.widgets.AppBarController;
 import com.android.car.ui.core.CarUi;
@@ -78,6 +80,7 @@ public class PlaybackFragment extends Fragment {
     private View mControlBarScrim;
     private PlaybackControlsActionBar mPlaybackControls;
     private PlaybackViewModel mPlaybackViewModel;
+    private MediaItemsRepository mMediaItemsRepository;
     private ViewGroup mSeekBarContainer;
     private SeekBar mSeekBar;
     private List<View> mViewsToHideForCustomActions;
@@ -118,9 +121,9 @@ public class PlaybackFragment extends Fragment {
      */
     public interface PlaybackFragmentListener {
         /**
-         * Invoked when the user clicks on the collapse button
+         * Invoked when the user clicks on a browse link
          */
-        void onCollapse();
+        void goToMediaItem(MediaSource source, MediaItemMetadata mediaItem);
     }
 
     @Override
@@ -133,6 +136,8 @@ public class PlaybackFragment extends Fragment {
     public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
         mPlaybackViewModel = PlaybackViewModel.get(getActivity().getApplication(),
                 MEDIA_SOURCE_MODE_PLAYBACK);
+        mMediaItemsRepository = MediaItemsRepository.get(getActivity().getApplication(),
+                MEDIA_SOURCE_MODE_PLAYBACK);
 
         Resources res = getResources();
         mAlbumBackground = view.findViewById(R.id.playback_background);
@@ -304,8 +309,12 @@ public class PlaybackFragment extends Fragment {
 
         Size maxArtSize = MediaAppConfig.getMediaItemsBitmapMaxSize(view.getContext());
         mMetadataController = new MetadataController(getViewLifecycleOwner(), mPlaybackViewModel,
-                title, artist, albumTitle, outerSeparator, curTime, innerSeparator, maxTime,
-                seekbar, albumArt, null, maxArtSize);
+                mMediaItemsRepository, title, artist, albumTitle, outerSeparator, curTime,
+                innerSeparator, maxTime, seekbar, albumArt, null, maxArtSize,
+                (mediaItem) -> {
+                    MediaSource source = mPlaybackViewModel.getMediaSource().getValue();
+                    mListener.goToMediaItem(source, mediaItem);
+                });
     }
 
     /**
diff --git a/src/com/android/car/media/browse/BrowseMiniMediaItemView.java b/src/com/android/car/media/browse/BrowseMiniMediaItemView.java
index 4631e15..16ea70f 100644
--- a/src/com/android/car/media/browse/BrowseMiniMediaItemView.java
+++ b/src/com/android/car/media/browse/BrowseMiniMediaItemView.java
@@ -68,8 +68,8 @@ public class BrowseMiniMediaItemView extends BrowseMiniMediaItemBar {
     /** Connects the bar to the {@link PlaybackViewModel}. */
     public void setModel(@NonNull PlaybackViewModel model, @NonNull LifecycleOwner owner,
                          @NonNull Size maxArtSize) {
-        mMetadataController = new MetadataController(owner, model, mTitle, mSubtitle, null, null,
-                null, null, null, null, mContentTile, mAppIcon, maxArtSize);
+        mMetadataController = new MetadataController(owner, model, null, mTitle, mSubtitle, null,
+                null, null, null, null, null, mContentTile, mAppIcon, maxArtSize, null);
         mPlaybackViewModel = model;
 
         if (mArtBinder != null) {
diff --git a/tests/unittests/src/com/android/car/media/BrowseStackTests.java b/tests/unittests/src/com/android/car/media/BrowseStackTests.java
new file mode 100644
index 0000000..f36765d
--- /dev/null
+++ b/tests/unittests/src/com/android/car/media/BrowseStackTests.java
@@ -0,0 +1,168 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.car.media;
+
+import static android.support.v4.media.MediaMetadataCompat.METADATA_KEY_DISPLAY_TITLE;
+
+import static com.android.car.media.BrowseStack.BrowseEntryType.LINK;
+import static com.android.car.media.BrowseStack.BrowseEntryType.LINK_BROWSE;
+import static com.android.car.media.BrowseStack.BrowseEntryType.SEARCH_BROWSE;
+import static com.android.car.media.BrowseStack.BrowseEntryType.SEARCH_RESULTS;
+import static com.android.car.media.BrowseStack.BrowseEntryType.TREE_BROWSE;
+import static com.android.car.media.BrowseStack.BrowseEntryType.TREE_ROOT;
+import static com.android.car.media.BrowseStack.BrowseEntryType.TREE_TAB;
+
+import static junit.framework.Assert.assertEquals;
+
+import static org.mockito.Mockito.mock;
+
+import android.support.v4.media.MediaMetadataCompat;
+
+import androidx.core.util.Preconditions;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+
+import com.android.car.media.BrowseStack.BrowseEntryType;
+import com.android.car.media.common.MediaItemMetadata;
+
+import com.google.common.collect.HashBiMap;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.util.ArrayList;
+
+@RunWith(AndroidJUnit4.class)
+public class BrowseStackTests extends BaseMockitoTest {
+
+    private final HashBiMap<BrowseEntryType, String> mTypeEncoding = HashBiMap.create();
+
+    @Before
+    public void setup() {
+        mTypeEncoding.put(TREE_ROOT,        "TR");
+        mTypeEncoding.put(TREE_TAB,         "TT");
+        mTypeEncoding.put(TREE_BROWSE,      "TB");
+        mTypeEncoding.put(SEARCH_RESULTS,   "SR");
+        mTypeEncoding.put(SEARCH_BROWSE,    "SB");
+        mTypeEncoding.put(LINK,             "LN");
+        mTypeEncoding.put(LINK_BROWSE,      "LB");
+    }
+
+    @Test
+    public void removeAllEntriesExceptRoot() {
+        BrowseStack stack = decodeStack("TR/TT:tab/TB:n1/SR/SB:s1/SB:s2/");
+        stack.removeAllEntriesExceptRoot();
+        assertEquals("TR/", encodeStack(stack));
+    }
+
+    @Test
+    public void removeTreeEntriesExceptRoot() {
+        BrowseStack stack = decodeStack("TR/TT:tab/TB:n1/SR/SB:s1/SB:s2/LN:l1/LB:l2/");
+        stack.removeTreeEntriesExceptRoot();
+        assertEquals("TR/SR/SB:s1/SB:s2/LN:l1/LB:l2/", encodeStack(stack));
+    }
+
+    @Test
+    public void removeTrailingSearchEntries() {
+        BrowseStack stack = decodeStack("TR/TT:tab/TB:n1/SR/SB:s1/SB:s2/");
+        stack.removeSearchEntries();
+        assertEquals("TR/TT:tab/TB:n1/", encodeStack(stack));
+    }
+
+    @Test
+    public void removeMiddleSearchEntries() {
+        BrowseStack stack = decodeStack("TR/SR/SB:s1/SB:s2/LN:l1/LB:l2/");
+        stack.removeSearchEntries();
+        assertEquals("TR/LN:l1/LB:l2/", encodeStack(stack));
+    }
+
+    @Test
+    public void removeTrailingObsoleteEntries() {
+        BrowseStack stack = decodeStack("TR/SR/SB:s1/SB:s2/LN:l1/LB:l2/");
+        removeObsoleteEntries(stack, 4, 5);
+        assertEquals("TR/SR/SB:s1/SB:s2/LN:l1/", encodeStack(stack));
+    }
+
+    @Test
+    public void removeObsoleteEntriesIgnoresIrrelevantItem() {
+        BrowseStack stack = decodeStack("TR/SR/SB:s1/SB:s2/LN:l1/LB:l2/");
+        removeObsoleteEntries(stack, 4, 2);
+        assertEquals("TR/SR/SB:s1/SB:s2/LN:l1/LB:l2/", encodeStack(stack));
+    }
+
+    @Test
+    public void removeMiddleObsoleteEntries() {
+        BrowseStack stack = decodeStack("TR/TT:tab/TB:n1/TB:n2/TB:n3/SR/SB:s1/SB:s2/");
+        removeObsoleteEntries(stack, 1, 2);
+        assertEquals("TR/TT:tab/SR/SB:s1/SB:s2/", encodeStack(stack));
+    }
+
+    /**
+     * Picks the controller and the item at the given index then calls removeObsoleteEntries.
+     */
+    private void removeObsoleteEntries(BrowseStack stack, int controllerIndex, int itemIndex) {
+        BrowseViewController ctrl = stack.getEntries().get(controllerIndex).getController();
+        ArrayList<MediaItemMetadata> list = new ArrayList<>(1);
+        list.add(stack.getEntries().get(itemIndex).mItem);
+        stack.removeObsoleteEntries(Preconditions.checkNotNull(ctrl), list);
+    }
+
+    private String encodeType(BrowseEntryType type) {
+        return Preconditions.checkNotNull(mTypeEncoding.get(type));
+    }
+
+    private BrowseEntryType decodeType(String code) {
+        return Preconditions.checkNotNull(mTypeEncoding.inverse().get(code));
+    }
+
+    private BrowseStack decodeStack(String encoded) {
+        BrowseStack result = new BrowseStack();
+        String[] entries = encoded.split("/");
+        for (String entry : entries) {
+            String[] codesAndNode = entry.split(":");
+            BrowseEntryType type = decodeType(codesAndNode[0]);
+            switch (type) {
+                case TREE_ROOT:
+                    result.pushRoot(mock(BrowseViewController.class));
+                    break;
+                case SEARCH_RESULTS:
+                    result.pushSearchResults(mock(BrowseViewController.class));
+                    break;
+                default:
+                    MediaMetadataCompat.Builder bob = new MediaMetadataCompat.Builder();
+                    bob.putText(METADATA_KEY_DISPLAY_TITLE, codesAndNode[1]);
+                    MediaItemMetadata item = new MediaItemMetadata(bob.build());
+                    result.pushEntry(type, item, mock(BrowseViewController.class));
+            }
+        }
+        return result;
+    }
+
+    private String encodeStack(BrowseStack stack) {
+        StringBuilder builder = new StringBuilder();
+        for (BrowseStack.BrowseEntry entry : stack.getEntries()) {
+            builder.append(encodeType(entry.mType));
+            if ((entry.mType != TREE_ROOT) && (entry.mType != SEARCH_RESULTS)) {
+                Preconditions.checkNotNull(entry.mItem);
+                builder.append(":");
+                builder.append(entry.mItem.getTitle());
+            }
+            builder.append("/");
+        }
+        return builder.toString();
+    }
+}
diff --git a/tests/unittests/src/com/android/car/media/browse/BrowseTestUtils.java b/tests/unittests/src/com/android/car/media/browse/BrowseTestUtils.java
index faa1488..3a58b07 100644
--- a/tests/unittests/src/com/android/car/media/browse/BrowseTestUtils.java
+++ b/tests/unittests/src/com/android/car/media/browse/BrowseTestUtils.java
@@ -34,7 +34,7 @@ public class BrowseTestUtils {
                 .setSubtitle("Parent")
                 .setDescription("Parent item desc")
                 .setMediaId("ParentItem");
-        return new MediaItemMetadata(builder.build(), 0L, true, false, "Parent", "Parent");
+        return new MediaItemMetadata(builder.build(), 0L, true, false, null);
     }
 
     public static List<MediaItemMetadata> generateTestItems() {
@@ -44,14 +44,14 @@ public class BrowseTestUtils {
                 .setDescription("Test item 1 desc")
                 .setMediaId("TestItem1");
         MediaItemMetadata browsableItem = new MediaItemMetadata(builder.build(), 1L, true, false,
-                "Item1", "Test1");
+                null);
 
         builder.setTitle("TestItem2")
                 .setSubtitle("Tester2")
                 .setDescription("Test item 2 desc")
                 .setMediaId("TestItem2");
         MediaItemMetadata playableItem = new MediaItemMetadata(builder.build(), 2L, false, true,
-                "Item2", "Test2");
+                null);
 
 
         Bundle extras = new Bundle();
@@ -66,8 +66,7 @@ public class BrowseTestUtils {
                 .setMediaId("TestItem3")
                 .setExtras(extras);
         MediaItemMetadata downloadedExplicitNewProgress = new MediaItemMetadata(builder.build(), 3L,
-                false, true,
-                "Item3", "Test3");
+                false, true, null);
 
         Bundle newExtras = new Bundle();
         newExtras.putLong("android.media.extra.DOWNLOAD_STATUS", 2L);
@@ -81,9 +80,7 @@ public class BrowseTestUtils {
                 .setMediaId("TestItem3")
                 .setExtras(newExtras);
         MediaItemMetadata downloadedExplicitNewProgress2 = new MediaItemMetadata(builder.build(),
-                3L,
-                false, true,
-                "Item3", "Test3");
+                3L, false, true, null);
 
         Bundle finishedPlayExtras = new Bundle();
         finishedPlayExtras.putLong("android.media.extra.DOWNLOAD_STATUS", 2L);
@@ -97,9 +94,7 @@ public class BrowseTestUtils {
                 .setMediaId("TestItem3")
                 .setExtras(finishedPlayExtras);
         MediaItemMetadata downloadedExplicitNewProgress3 = new MediaItemMetadata(builder.build(),
-                3L,
-                false, true,
-                "Item3", "Test3");
+                3L, false, true, null);
 
         List<MediaItemMetadata> itemList = new ArrayList<>();
         itemList.add(browsableItem);
diff --git a/tools/generate-overlayable.sh b/tools/generate-overlayable.sh
index b6fe78a..7d51a0c 100755
--- a/tools/generate-overlayable.sh
+++ b/tools/generate-overlayable.sh
@@ -15,15 +15,18 @@
 
 # Run this script to regenerate the overlayable.xml file.
 
-if [[ -z "$ANDROID_BUILD_TOP" ]]; then
-  echo 'ANDROID_BUILD_TOP environment variable is empty; did you forget to run `lunch`?'
-  exit 1
-fi
+cd $(dirname $0)
+cd ..
 
-PROJECT_TOP=$ANDROID_BUILD_TOP/packages/apps/Car/Media
+PROJECT_TOP="$(pwd)"
+export PROJECT_TOP
+cd ../../../..
+
+ANDROID_BUILD_TOP="$(pwd)"
+export ANDROID_BUILD_TOP
 
 python3 $ANDROID_BUILD_TOP/packages/apps/Car/tests/tools/rro/generate-overlayable.py \
     -n CarMediaApp \
     -r $PROJECT_TOP/res \
     -e $PROJECT_TOP/res/values/overlayable.xml $PROJECT_TOP/res/xml/automotive_app_desc.xml $PROJECT_TOP/res/values/colors.xml $PROJECT_TOP/res/values/dimens.xml $PROJECT_TOP/res/color/progress_bar_thumb_inner_ring_color.xml $PROJECT_TOP/res/color/progress_bar_thumb_outer_ring_color.xml \
-    -o $PROJECT_TOP/res/values/overlayable.xml
\ No newline at end of file
+    -o $PROJECT_TOP/res/values/overlayable.xml