DO NOT MERGE - Merge Android 13

Bug: 242648940
Merged-In: I83952c087db24a978729f4cff5d2f2cc203ec38f
Change-Id: I696b32e73e0a18a74cdd1c905e8ca409e9390b55

16 files changed, 487 insertions, 397 deletions

diff --git a/apex/aidl/private/android/media/IMediaCommunicationService.aidl b/apex/aidl/private/android/media/IMediaCommunicationService.aidl
index fb3172b..e1c89e9 100644
--- a/apex/aidl/private/android/media/IMediaCommunicationService.aidl
+++ b/apex/aidl/private/android/media/IMediaCommunicationService.aidl
@@ -18,6 +18,7 @@ package android.media;
 import android.media.Session2Token;
 import android.media.IMediaCommunicationServiceCallback;
 import android.media.MediaParceledListSlice;
+import android.view.KeyEvent;
 
 /** {@hide} */
 interface IMediaCommunicationService {
@@ -25,6 +26,8 @@ interface IMediaCommunicationService {
     boolean isTrusted(String controllerPackageName, int controllerPid, int controllerUid);
     MediaParceledListSlice getSession2Tokens(int userId);
 
+   void dispatchMediaKeyEvent(String packageName, in KeyEvent keyEvent, boolean asSystemService);
+
     void registerCallback(IMediaCommunicationServiceCallback callback, String packageName);
     void unregisterCallback(IMediaCommunicationServiceCallback callback);
 }
diff --git a/apex/framework/Android.bp b/apex/framework/Android.bp
index a5e6df1..7bba456 100644
--- a/apex/framework/Android.bp
+++ b/apex/framework/Android.bp
@@ -17,17 +17,20 @@ package {
     default_applicable_licenses: ["Android-Apache-2.0"],
 }
 
+// The dex jar produced by this is used in the APEX but otherwise this is not
+// used.
 java_library {
     name: "updatable-media",
 
-    srcs: [
-        ":updatable-media-srcs",
+    static_libs: [
+        "framework-media.impl",
     ],
 
     permitted_packages: [
         "android.media",
     ],
 
+    // Optimize the dex jar for the APEX.
     optimize: {
         enabled: true,
         shrink: true,
@@ -37,19 +40,6 @@ java_library {
     installable: true,
 
     sdk_version: "module_current",
-    libs: [
-        "androidx.annotation_annotation",
-        "framework-annotations-lib",
-    ],
-    static_libs: [
-        "exoplayer2-extractor",
-        "mediatranscoding_aidl_interface-java",
-        "modules-annotation-minsdk",
-        "modules-utils-build",
-    ],
-    jarjar_rules: "jarjar_rules.txt",
-
-    plugins: ["java_api_finder"],
 
     hostdex: true, // for hiddenapi check
     apex_available: [
@@ -58,10 +48,9 @@ java_library {
     ],
     min_sdk_version: "29",
     visibility: [
+        // This MUST not be used for compilation within the media module, use
+        // framework-media.impl instead.
         "//frameworks/av/apex:__subpackages__",
-        "//frameworks/base/apex/media/service",
-        "//frameworks/base/api", // For framework-all
-        "//packages/modules/Media/apex/service",
     ],
 }
 
@@ -126,14 +115,38 @@ java_sdk_library {
     name: "framework-media",
     defaults: ["framework-module-defaults"],
 
-    // This is only used to define the APIs for updatable-media.
-    api_only: true,
-
     srcs: [
         ":updatable-media-srcs",
     ],
 
-    impl_library_visibility: ["//frameworks/av/apex:__subpackages__"],
+    impl_library_visibility: [
+        "//frameworks/base/api", // For framework-all
+        "//packages/modules/Media:__subpackages__",
+    ],
+
+    sdk_version: "module_current",
+    impl_only_libs: [
+        "androidx.annotation_annotation",
+        "framework-annotations-lib",
+    ],
+    impl_only_static_libs: [
+        "exoplayer-media_apex",
+        "mediatranscoding_aidl_interface-java",
+        "modules-annotation-minsdk",
+        "modules-utils-build",
+    ],
+    jarjar_rules: "jarjar_rules.txt",
+
+    plugins: ["java_api_finder"],
+
+    apex_available: [
+        "com.android.media",
+        "test_com.android.media",
+    ],
+    lint: {
+        strict_updatability_linting: true,
+    },
+    min_sdk_version: "29",
 }
 
 cc_library_shared {
diff --git a/apex/framework/api/module-lib-current.txt b/apex/framework/api/module-lib-current.txt
index eb6397a..7317f14 100644
--- a/apex/framework/api/module-lib-current.txt
+++ b/apex/framework/api/module-lib-current.txt
@@ -2,6 +2,7 @@
 package android.media {
 
   public class MediaCommunicationManager {
+    method public void dispatchMediaKeyEvent(@NonNull android.view.KeyEvent, boolean);
     method @RequiresPermission(android.Manifest.permission.MEDIA_CONTENT_CONTROL) public void registerSessionCallback(@NonNull java.util.concurrent.Executor, @NonNull android.media.MediaCommunicationManager.SessionCallback);
     method public void unregisterSessionCallback(@NonNull android.media.MediaCommunicationManager.SessionCallback);
   }
diff --git a/apex/framework/java/android/media/BaseMediaParceledListSlice.java b/apex/framework/java/android/media/BaseMediaParceledListSlice.java
index fb66609..11db293 100644
--- a/apex/framework/java/android/media/BaseMediaParceledListSlice.java
+++ b/apex/framework/java/android/media/BaseMediaParceledListSlice.java
@@ -43,7 +43,7 @@ import java.util.List;
  */
 abstract class BaseMediaParceledListSlice<T> implements Parcelable {
     private static String TAG = "BaseMediaParceledListSlice";
-    private static boolean DEBUG = false;
+    private static final boolean DEBUG = false;
 
     /*
      * TODO get this number from somewhere else. For now set it to a quarter of
@@ -107,7 +107,11 @@ abstract class BaseMediaParceledListSlice<T> implements Parcelable {
             }
             while (i < N && reply.readInt() != 0) {
                 final T parcelable = readCreator(creator, reply, loader);
-                verifySameType(listElementClass, parcelable.getClass());
+                if (listElementClass == null) {
+                    listElementClass = parcelable.getClass();
+                } else {
+                    verifySameType(listElementClass, parcelable.getClass());
+                }
 
                 mList.add(parcelable);
 
diff --git a/apex/framework/java/android/media/MediaCommunicationManager.java b/apex/framework/java/android/media/MediaCommunicationManager.java
index 40992f1..d6442d4 100644
--- a/apex/framework/java/android/media/MediaCommunicationManager.java
+++ b/apex/framework/java/android/media/MediaCommunicationManager.java
@@ -32,6 +32,9 @@ import android.os.RemoteException;
 import android.os.UserHandle;
 import android.service.media.MediaBrowserService;
 import android.util.Log;
+import android.view.KeyEvent;
+
+import androidx.annotation.RequiresApi;
 
 import androidx.annotation.RequiresApi;
 
@@ -66,7 +69,8 @@ public class MediaCommunicationManager {
     private static final int CURRENT_VERSION = VERSION_1;
 
     private final Context mContext;
-    private final IMediaCommunicationService mService;
+    // Do not access directly use getService().
+    private IMediaCommunicationService mService;
 
     private final Object mLock = new Object();
     private final CopyOnWriteArrayList<SessionCallbackRecord> mTokenCallbackRecords =
@@ -75,6 +79,9 @@ public class MediaCommunicationManager {
     @GuardedBy("mLock")
     private MediaCommunicationServiceCallbackStub mCallbackStub;
 
+    // TODO: remove this when MCS implements dispatchMediaKeyEvent.
+    private MediaSessionManager mMediaSessionManager;
+
     /**
      * @hide
      */
@@ -83,10 +90,6 @@ public class MediaCommunicationManager {
             throw new UnsupportedOperationException("Android version must be S or greater.");
         }
         mContext = context;
-        mService = IMediaCommunicationService.Stub.asInterface(
-                MediaFrameworkInitializer.getMediaServiceManager()
-                        .getMediaCommunicationServiceRegisterer()
-                        .get());
     }
 
     /**
@@ -108,7 +111,7 @@ public class MediaCommunicationManager {
             throw new IllegalArgumentException("token's type should be TYPE_SESSION");
         }
         try {
-            mService.notifySession2Created(token);
+            getService().notifySession2Created(token);
         } catch (RemoteException e) {
             e.rethrowFromSystemServer();
         }
@@ -133,7 +136,7 @@ public class MediaCommunicationManager {
             return false;
         }
         try {
-            return mService.isTrusted(
+            return getService().isTrusted(
                     userInfo.getPackageName(), userInfo.getPid(), userInfo.getUid());
         } catch (RemoteException e) {
             Log.w(TAG, "Cannot communicate with the service.", e);
@@ -185,7 +188,7 @@ public class MediaCommunicationManager {
                 MediaCommunicationServiceCallbackStub callbackStub =
                         new MediaCommunicationServiceCallbackStub();
                 try {
-                    mService.registerCallback(callbackStub, mContext.getPackageName());
+                    getService().registerCallback(callbackStub, mContext.getPackageName());
                     mCallbackStub = callbackStub;
                 } catch (RemoteException ex) {
                     Log.e(TAG, "Failed to register callback.", ex);
@@ -208,7 +211,7 @@ public class MediaCommunicationManager {
         synchronized (mLock) {
             if (mCallbackStub != null && mTokenCallbackRecords.isEmpty()) {
                 try {
-                    mService.unregisterCallback(mCallbackStub);
+                    getService().unregisterCallback(mCallbackStub);
                 } catch (RemoteException ex) {
                     Log.e(TAG, "Failed to unregister callback.", ex);
                 }
@@ -217,9 +220,27 @@ public class MediaCommunicationManager {
         }
     }
 
+    private IMediaCommunicationService getService() {
+        if (mService == null) {
+            mService = IMediaCommunicationService.Stub.asInterface(
+                    MediaFrameworkInitializer.getMediaServiceManager()
+                            .getMediaCommunicationServiceRegisterer()
+                            .get());
+        }
+        return mService;
+    }
+
+    // TODO: remove this when MCS implements dispatchMediaKeyEvent.
+    private MediaSessionManager getMediaSessionManager() {
+        if (mMediaSessionManager == null) {
+            mMediaSessionManager = mContext.getSystemService(MediaSessionManager.class);
+        }
+        return mMediaSessionManager;
+    }
+
     private List<Session2Token> getSession2Tokens(int userId) {
         try {
-            MediaParceledListSlice slice = mService.getSession2Tokens(userId);
+            MediaParceledListSlice slice = getService().getSession2Tokens(userId);
             return slice == null ? Collections.emptyList() : slice.getList();
         } catch (RemoteException e) {
             Log.e(TAG, "Failed to get session tokens", e);
@@ -228,6 +249,34 @@ public class MediaCommunicationManager {
     }
 
     /**
+     * Sends a media key event. The receiver will be selected automatically.
+     *
+     * @param keyEvent the key event to send, non-media key events will be ignored.
+     * @param asSystemService if {@code true}, the event is sent to the session as if it was come
+     *                        from the system service instead of the app process. It only affects
+     *                        {@link MediaSession.Callback#getCurrentControllerInfo()}.
+     * @hide
+     */
+    @SystemApi(client = SystemApi.Client.MODULE_LIBRARIES)
+    public void dispatchMediaKeyEvent(@NonNull KeyEvent keyEvent, boolean asSystemService) {
+        Objects.requireNonNull(keyEvent, "keyEvent shouldn't be null");
+
+        // When MCS handles this, caller is changed.
+        // TODO: remove this when MCS implementation is done.
+        if (!asSystemService) {
+            getMediaSessionManager().dispatchMediaKeyEvent(keyEvent, false);
+            return;
+        }
+
+        try {
+            getService().dispatchMediaKeyEvent(mContext.getPackageName(),
+                    keyEvent, asSystemService);
+        } catch (RemoteException e) {
+            Log.e(TAG, "Failed to send key event.", e);
+        }
+    }
+
+    /**
      * Callback for listening to changes to the sessions.
      * @see #registerSessionCallback(Executor, SessionCallback)
      * @hide
diff --git a/apex/framework/java/android/media/MediaSession2.java b/apex/framework/java/android/media/MediaSession2.java
index e76d61c..7d07eb3 100644
--- a/apex/framework/java/android/media/MediaSession2.java
+++ b/apex/framework/java/android/media/MediaSession2.java
@@ -262,7 +262,7 @@ public class MediaSession2 implements AutoCloseable {
     }
 
     /**
-     * Returns whehther the playback is active (i.e. playing something)
+     * Returns whether the playback is active (i.e. playing something)
      *
      * @return {@code true} if the playback active, {@code false} otherwise.
      */
@@ -302,8 +302,9 @@ public class MediaSession2 implements AutoCloseable {
             parcel.setDataPosition(0);
             Bundle out = parcel.readBundle(null);
 
-            // Calling Bundle#size() will trigger Bundle#unparcel().
-            out.size();
+            for (String key : out.keySet()) {
+                out.get(key);
+            }
         } catch (BadParcelableException e) {
             Log.d(TAG, "Custom parcelable in bundle.", e);
             return true;
diff --git a/apex/framework/java/android/media/MediaSession2Service.java b/apex/framework/java/android/media/MediaSession2Service.java
index f6fd509..9f80c43 100644
--- a/apex/framework/java/android/media/MediaSession2Service.java
+++ b/apex/framework/java/android/media/MediaSession2Service.java
@@ -161,19 +161,19 @@ public abstract class MediaSession2Service extends Service {
     public abstract MediaSession2 onGetSession(@NonNull ControllerInfo controllerInfo);
 
     /**
-     * Called when notification UI needs update. Override this method to show or cancel your own
-     * notification UI.
+     * Called to update the media notification when the playback state changes.
      * <p>
-     * This would be called on {@link MediaSession2}'s callback executor when playback state is
-     * changed.
+     * If playback is active and a notification is returned, the service uses it to become a
+     * foreground service. If playback is not active then the notification is still posted, but the
+     * service does not become a foreground service.
      * <p>
-     * With the notification returned here, the service becomes foreground service when the playback
-     * is started. Apps must request the permission
-     * {@link android.Manifest.permission#FOREGROUND_SERVICE} in order to use this API. It becomes
-     * background service after the playback is stopped.
+     * Apps must request the {@link android.Manifest.permission#FOREGROUND_SERVICE} permission
+     * in order to use this API. For apps targeting {@link android.os.Build.VERSION_CODES#TIRAMISU}
+     * or later, notifications will only be posted if the app has also been granted the
+     * {@link android.Manifest.permission#POST_NOTIFICATIONS} permission.
      *
-     * @param session a session that needs notification update.
-     * @return a {@link MediaNotification}. Can be {@code null}.
+     * @param session the session for which an updated media notification is required.
+     * @return the {@link MediaNotification}. Can be {@code null}.
      */
     @Nullable
     public abstract MediaNotification onUpdateNotification(@NonNull MediaSession2 session);
diff --git a/apex/framework/java/android/media/MediaTranscodingManager.java b/apex/framework/java/android/media/MediaTranscodingManager.java
index ca35c01..aff3204 100644
--- a/apex/framework/java/android/media/MediaTranscodingManager.java
+++ b/apex/framework/java/android/media/MediaTranscodingManager.java
@@ -22,7 +22,6 @@ import android.annotation.IntRange;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.annotation.SystemApi;
-import android.app.ActivityManager;
 import android.content.ContentResolver;
 import android.content.Context;
 import android.content.res.AssetFileDescriptor;
@@ -124,7 +123,6 @@ public final class MediaTranscodingManager {
     private final String mPackageName;
     private final int mPid;
     private final int mUid;
-    private final boolean mIsLowRamDevice;
     private final ExecutorService mExecutor = Executors.newSingleThreadExecutor();
     private final HashMap<Integer, TranscodingSession> mPendingTranscodingSessions = new HashMap();
     private final Object mLock = new Object();
@@ -211,10 +209,7 @@ public final class MediaTranscodingManager {
         if (!SdkLevel.isAtLeastS()) {
             return null;
         }
-        // Do not try to get the service on AndroidGo (low-ram) devices.
-        if (mIsLowRamDevice) {
-            return null;
-        }
+
         int retryCount = !retry ? 1 :  CONNECT_SERVICE_RETRY_COUNT;
         Log.i(TAG, "get service with retry " + retryCount);
         for (int count = 1;  count <= retryCount; count++) {
@@ -432,7 +427,6 @@ public final class MediaTranscodingManager {
         mPackageName = mContext.getPackageName();
         mUid = Os.getuid();
         mPid = Os.getpid();
-        mIsLowRamDevice = mContext.getSystemService(ActivityManager.class).isLowRamDevice();
     }
 
     /**
diff --git a/apex/framework/java/android/media/Session2Command.java b/apex/framework/java/android/media/Session2Command.java
index 26f4568..7e71591 100644
--- a/apex/framework/java/android/media/Session2Command.java
+++ b/apex/framework/java/android/media/Session2Command.java
@@ -37,9 +37,8 @@ import java.util.Objects;
  * If {@link #getCommandCode()} is {@link #COMMAND_CODE_CUSTOM}), it's custom command and
  * {@link #getCustomAction()} shouldn't be {@code null}.
  * <p>
- * Refer to the
- * <a href="{@docRoot}reference/androidx/media2/SessionCommand2.html">AndroidX SessionCommand</a>
- * class for the list of valid commands.
+ * Refer to the <a href="{@docRoot}reference/androidx/media2/session/SessionCommand.html">
+ * AndroidX SessionCommand</a> class for the list of valid commands.
  */
 public final class Session2Command implements Parcelable {
     /**
diff --git a/apex/framework/java/android/media/Session2CommandGroup.java b/apex/framework/java/android/media/Session2CommandGroup.java
index 13aabfc..af8184a 100644
--- a/apex/framework/java/android/media/Session2CommandGroup.java
+++ b/apex/framework/java/android/media/Session2CommandGroup.java
@@ -68,7 +68,7 @@ public final class Session2CommandGroup implements Parcelable {
     /**
      * Used by parcelable creator.
      */
-    @SuppressWarnings("WeakerAccess") /* synthetic access */
+    @SuppressWarnings({"WeakerAccess", "UnsafeParcelApi"}) /* synthetic access */
     Session2CommandGroup(Parcel in) {
         Parcelable[] commands = in.readParcelableArray(Session2Command.class.getClassLoader());
         if (commands != null) {
diff --git a/apex/framework/lint-baseline.xml b/apex/framework/lint-baseline.xml
index e1b1450..95eea45 100644
--- a/apex/framework/lint-baseline.xml
+++ b/apex/framework/lint-baseline.xml
@@ -1,312 +1,70 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<issues format="5" by="lint 4.1.0" client="cli" variant="all" version="4.1.0">
+<issues format="6" by="lint 7.2.0-dev" type="baseline" client="" dependencies="true" name="" variant="all" version="7.2.0-dev">
 
     <issue
-        id="NewApi"
-        message="Call requires API level 31 (current min is 29): `new android.media.ApplicationMediaCapabilities.Builder`"
-        errorLine1="                            new ApplicationMediaCapabilities.Builder();"
-        errorLine2="                            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
+        id="DefaultLocale"
+        message="Implicitly using the default locale is a common source of bugs: Use `toLowerCase(Locale)` instead. For strings meant to be internal use `Locale.ROOT`, otherwise `Locale.getDefault()`."
+        errorLine1="        if (mSupportedVideoMimeTypes.contains(videoMime.toLowerCase())) {"
+        errorLine2="                                                        ~~~~~~~~~~~">
         <location
             file="frameworks/base/apex/media/framework/java/android/media/ApplicationMediaCapabilities.java"
-            line="208"
-            column="29"/>
+            line="121"
+            column="57"/>
     </issue>
 
     <issue
-        id="NewApi"
-        message="Call requires API level 31 (current min is 29): `new android.media.ApplicationMediaCapabilities.Builder`"
-        errorLine1="        ApplicationMediaCapabilities.Builder builder = new ApplicationMediaCapabilities.Builder();"
-        errorLine2="                                                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
+        id="DefaultLocale"
+        message="Implicitly using the default locale is a common source of bugs: Use `String.format(Locale, ...)` instead"
+        errorLine1="            return String.format(&quot; session: {id: %d, status: %s, result: %s, progress: %d}&quot;,"
+        errorLine2="                   ^">
         <location
-            file="frameworks/base/apex/media/framework/java/android/media/ApplicationMediaCapabilities.java"
-            line="314"
-            column="56"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Call requires API level R (current min is 29): `android.os.RemoteException#rethrowFromSystemServer`"
-        errorLine1="            e.rethrowFromSystemServer();"
-        errorLine2="              ~~~~~~~~~~~~~~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaCommunicationManager.java"
-            line="110"
-            column="15"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Call requires API level R (current min is 29): `android.os.Parcel#writeParcelableCreator`"
-        errorLine1="        dest.writeParcelableCreator((Parcelable) parcelable);"
-        errorLine2="             ~~~~~~~~~~~~~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParceledListSlice.java"
-            line="77"
-            column="14"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Call requires API level R (current min is 29): `android.os.Parcel#readParcelableCreator`"
-        errorLine1="        return from.readParcelableCreator(loader);"
-        errorLine2="                    ~~~~~~~~~~~~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParceledListSlice.java"
-            line="82"
-            column="21"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.TrackData#mediaFormat`"
-        errorLine1="            this.mediaFormat = mediaFormat;"
-        errorLine2="            ~~~~~~~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="273"
-            column="13"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.TrackData#drmInitData`"
-        errorLine1="            this.drmInitData = drmInitData;"
-        errorLine2="            ~~~~~~~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="274"
-            column="13"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.SeekPoint#timeMicros`"
-        errorLine1="            this.timeMicros = timeMicros;"
-        errorLine2="            ~~~~~~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="295"
-            column="13"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.SeekPoint#position`"
-        errorLine1="            this.position = position;"
-        errorLine2="            ~~~~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="296"
-            column="13"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.SeekPoint#position`"
-        errorLine1="            return &quot;[timeMicros=&quot; + timeMicros + &quot;, position=&quot; + position + &quot;]&quot;;"
-        errorLine2="                                                                 ~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="302"
-            column="66"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.SeekPoint#timeMicros`"
-        errorLine1="            return &quot;[timeMicros=&quot; + timeMicros + &quot;, position=&quot; + position + &quot;]&quot;;"
-        errorLine2="                                    ~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="302"
-            column="37"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Class requires API level R (current min is 29): `android.media.MediaParser.SeekPoint`"
-        errorLine1="            SeekPoint other = (SeekPoint) obj;"
-        errorLine2="                               ~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="313"
-            column="32"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.SeekPoint#position`"
-        errorLine1="            return timeMicros == other.timeMicros &amp;&amp; position == other.position;"
-        errorLine2="                                                     ~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="314"
-            column="54"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.SeekPoint#position`"
-        errorLine1="            return timeMicros == other.timeMicros &amp;&amp; position == other.position;"
-        errorLine2="                                                                 ~~~~~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="314"
-            column="66"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.SeekPoint#timeMicros`"
-        errorLine1="            return timeMicros == other.timeMicros &amp;&amp; position == other.position;"
-        errorLine2="                   ~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="314"
+            file="frameworks/base/apex/media/framework/java/android/media/MediaTranscodingManager.java"
+            line="1651"
             column="20"/>
     </issue>
 
     <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.SeekPoint#timeMicros`"
-        errorLine1="            return timeMicros == other.timeMicros &amp;&amp; position == other.position;"
-        errorLine2="                                 ~~~~~~~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="314"
-            column="34"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.SeekPoint#timeMicros`"
-        errorLine1="            int result = (int) timeMicros;"
-        errorLine2="                               ~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="319"
-            column="32"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.SeekPoint#position`"
-        errorLine1="            result = 31 * result + (int) position;"
-        errorLine2="                                         ~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="320"
-            column="42"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Class requires API level R (current min is 29): `android.media.MediaParser.InputReader`"
-        errorLine1="    public interface SeekableInputReader extends InputReader {"
-        errorLine2="                                                 ~~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="352"
-            column="50"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level 31 (current min is 29): `android.media.metrics.LogSessionId#LOG_SESSION_ID_NONE`"
-        errorLine1="    @NonNull private LogSessionId mLogSessionId = LogSessionId.LOG_SESSION_ID_NONE;"
-        errorLine2="                                                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="1071"
-            column="51"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Cast from `SeekableInputReader` to `InputReader` requires API level 30 (current min is 29)"
-        errorLine1="        mExoDataReader.mInputReader = seekableInputReader;"
-        errorLine2="                                      ~~~~~~~~~~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="1201"
-            column="39"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.SeekPoint#position`"
-        errorLine1="            mPendingSeekPosition = seekPoint.position;"
-        errorLine2="                                   ~~~~~~~~~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="1287"
-            column="36"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.SeekPoint#timeMicros`"
-        errorLine1="            mPendingSeekTimeMicros = seekPoint.timeMicros;"
-        errorLine2="                                     ~~~~~~~~~~~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="1288"
-            column="38"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.SeekPoint#position`"
-        errorLine1="            mExtractor.seek(seekPoint.position, seekPoint.timeMicros);"
-        errorLine2="                            ~~~~~~~~~~~~~~~~~~">
-        <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="1290"
-            column="29"/>
-    </issue>
-
-    <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.MediaParser.SeekPoint#timeMicros`"
-        errorLine1="            mExtractor.seek(seekPoint.position, seekPoint.timeMicros);"
-        errorLine2="                                                ~~~~~~~~~~~~~~~~~~~~">
+        id="ParcelClassLoader"
+        message="Passing null here (to use the default class loader) will not work if you are restoring your own classes. Consider using for example `getClass().getClassLoader()` instead."
+        errorLine1="            Bundle out = parcel.readBundle(null);"
+        errorLine2="                                ~~~~~~~~~~~~~~~~">
         <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="1290"
-            column="49"/>
+            file="frameworks/base/apex/media/framework/java/android/media/MediaSession2.java"
+            line="303"
+            column="33"/>
     </issue>
 
     <issue
-        id="NewApi"
-        message="Field requires API level R (current min is 29): `android.media.DrmInitData.SchemeInitData#uuid`"
-        errorLine1="                if (schemeInitData.uuid.equals(schemeUuid)) {"
-        errorLine2="                    ~~~~~~~~~~~~~~~~~~~">
+        id="ParcelClassLoader"
+        message="Using the default class loader will not work if you are restoring your own classes. Consider using for example `readBundle(getClass().getClassLoader())` instead."
+        errorLine1="        mCustomExtras = in.readBundle();"
+        errorLine2="                           ~~~~~~~~~~~~">
         <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="1579"
-            column="21"/>
+            file="frameworks/base/apex/media/framework/java/android/media/Session2Command.java"
+            line="104"
+            column="28"/>
     </issue>
 
     <issue
-        id="NewApi"
-        message="Class requires API level R (current min is 29): `android.media.MediaParser.InputReader`"
-        errorLine1="    private static final class DataReaderAdapter implements InputReader {"
-        errorLine2="                                                            ~~~~~~~~~~~">
+        id="ParcelClassLoader"
+        message="Passing null here (to use the default class loader) will not work if you are restoring your own classes. Consider using for example `getClass().getClassLoader()` instead."
+        errorLine1="        mSessionLink = in.readParcelable(null);"
+        errorLine2="                          ~~~~~~~~~~~~~~~~~~~~">
         <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="1872"
-            column="61"/>
+            file="frameworks/base/apex/media/framework/java/android/media/Session2Token.java"
+            line="141"
+            column="27"/>
     </issue>
 
     <issue
-        id="NewApi"
-        message="Class requires API level R (current min is 29): `android.media.MediaParser.InputReader`"
-        errorLine1="    private static final class ParsableByteArrayAdapter implements InputReader {"
-        errorLine2="                                                                   ~~~~~~~~~~~">
+        id="ParcelClassLoader"
+        message="Using the default class loader will not work if you are restoring your own classes. Consider using for example `readBundle(getClass().getClassLoader())` instead."
+        errorLine1="        Bundle extras = in.readBundle();"
+        errorLine2="                           ~~~~~~~~~~~~">
         <location
-            file="frameworks/base/apex/media/framework/java/android/media/MediaParser.java"
-            line="1905"
-            column="68"/>
+            file="frameworks/base/apex/media/framework/java/android/media/Session2Token.java"
+            line="144"
+            column="28"/>
     </issue>
 
 </issues>
diff --git a/apex/service/Android.bp b/apex/service/Android.bp
index 60ff769..5f5eb54 100644
--- a/apex/service/Android.bp
+++ b/apex/service/Android.bp
@@ -36,11 +36,16 @@ java_sdk_library {
     ],
     libs: [
         "androidx.annotation_annotation",
-        "updatable-media",
+        "framework-media.impl",
         "modules-annotation-minsdk",
+        "modules-utils-build",
     ],
+    jarjar_rules: "jarjar_rules.txt",
     sdk_version: "system_server_current",
     min_sdk_version: "29", // TODO: We may need to bump this at some point.
+    lint: {
+        strict_updatability_linting: true,
+    },
     apex_available: [
         "com.android.media",
     ],
diff --git a/apex/service/jarjar_rules.txt b/apex/service/jarjar_rules.txt
new file mode 100644
index 0000000..7e37c2b
--- /dev/null
+++ b/apex/service/jarjar_rules.txt
@@ -0,0 +1 @@
+rule com.android.modules.** android.media.internal.@1
diff --git a/apex/service/java/com/android/server/media/MediaCommunicationService.java b/apex/service/java/com/android/server/media/MediaCommunicationService.java
index 0dc3e79..4223fa6 100644
--- a/apex/service/java/com/android/server/media/MediaCommunicationService.java
+++ b/apex/service/java/com/android/server/media/MediaCommunicationService.java
@@ -31,6 +31,7 @@ import android.media.MediaController2;
 import android.media.MediaParceledListSlice;
 import android.media.Session2CommandGroup;
 import android.media.Session2Token;
+import android.media.session.MediaSessionManager;
 import android.os.Binder;
 import android.os.Build;
 import android.os.Handler;
@@ -43,6 +44,7 @@ import android.os.UserManager;
 import android.util.Log;
 import android.util.SparseArray;
 import android.util.SparseIntArray;
+import android.view.KeyEvent;
 
 import androidx.annotation.RequiresApi;
 
@@ -56,7 +58,6 @@ import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
-import java.util.stream.Collectors;
 
 /**
  * A system service that manages {@link android.media.MediaSession2} creations
@@ -66,7 +67,7 @@ import java.util.stream.Collectors;
 @MinSdk(Build.VERSION_CODES.S)
 @RequiresApi(Build.VERSION_CODES.S)
 public class MediaCommunicationService extends SystemService {
-    private static final String TAG = "MediaCommunicationService";
+    private static final String TAG = "MediaCommunicationSrv";
     private static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG);
 
     final Context mContext;
@@ -81,8 +82,9 @@ public class MediaCommunicationService extends SystemService {
 
     final Executor mRecordExecutor = Executors.newSingleThreadExecutor();
     @GuardedBy("mLock")
-    final List<CallbackRecord> mCallbackRecords = new ArrayList<>();
+    final ArrayList<CallbackRecord> mCallbackRecords = new ArrayList<>();
     final NotificationManager mNotificationManager;
+    MediaSessionManager mSessionManager;
 
     public MediaCommunicationService(Context context) {
         super(context);
@@ -97,6 +99,17 @@ public class MediaCommunicationService extends SystemService {
     }
 
     @Override
+    public void onBootPhase(int phase) {
+        super.onBootPhase(phase);
+        switch (phase) {
+            // This ensures MediaSessionService is started
+            case PHASE_BOOT_COMPLETED:
+                mSessionManager = mContext.getSystemService(MediaSessionManager.class);
+                break;
+        }
+    }
+
+    @Override
     public void onUserStarting(@NonNull TargetUser user) {
         if (DEBUG) Log.d(TAG, "onUserStarting: " + user);
         updateUser();
@@ -140,8 +153,8 @@ public class MediaCommunicationService extends SystemService {
         return null;
     }
 
-    List<Session2Token> getSession2TokensLocked(int userId) {
-        List<Session2Token> list = new ArrayList<>();
+    ArrayList<Session2Token> getSession2TokensLocked(int userId) {
+        ArrayList<Session2Token> list = new ArrayList<>();
         if (userId == ALL.getIdentifier()) {
             int size = mUserRecords.size();
             for (int i = 0; i < size; i++) {
@@ -227,28 +240,29 @@ public class MediaCommunicationService extends SystemService {
     }
 
     void dispatchSession2Changed(int userId) {
-        MediaParceledListSlice<Session2Token> allSession2Tokens;
-        MediaParceledListSlice<Session2Token> userSession2Tokens;
+        ArrayList<Session2Token> allSession2Tokens;
+        ArrayList<Session2Token> userSession2Tokens;
 
         synchronized (mLock) {
-            allSession2Tokens =
-                    new MediaParceledListSlice<>(getSession2TokensLocked(ALL.getIdentifier()));
-            userSession2Tokens = new MediaParceledListSlice<>(getSession2TokensLocked(userId));
-        }
-        allSession2Tokens.setInlineCountLimit(1);
-        userSession2Tokens.setInlineCountLimit(1);
+            allSession2Tokens = getSession2TokensLocked(ALL.getIdentifier());
+            userSession2Tokens = getSession2TokensLocked(userId);
 
-        synchronized (mLock) {
             for (CallbackRecord record : mCallbackRecords) {
                 if (record.mUserId == ALL.getIdentifier()) {
                     try {
-                        record.mCallback.onSession2Changed(allSession2Tokens);
+                        MediaParceledListSlice<Session2Token> toSend =
+                                new MediaParceledListSlice<>(allSession2Tokens);
+                        toSend.setInlineCountLimit(0);
+                        record.mCallback.onSession2Changed(toSend);
                     } catch (RemoteException e) {
                         Log.w(TAG, "Failed to notify session2 tokens changed " + record);
                     }
                 } else if (record.mUserId == userId) {
                     try {
-                        record.mCallback.onSession2Changed(userSession2Tokens);
+                        MediaParceledListSlice<Session2Token> toSend =
+                                new MediaParceledListSlice<>(userSession2Tokens);
+                        toSend.setInlineCountLimit(0);
+                        record.mCallback.onSession2Changed(toSend);
                     } catch (RemoteException e) {
                         Log.w(TAG, "Failed to notify session2 tokens changed " + record);
                     }
@@ -273,6 +287,34 @@ public class MediaCommunicationService extends SystemService {
         session.close();
     }
 
+    void onSessionPlaybackStateChanged(Session2Record session, boolean promotePriority) {
+        FullUserRecord user = session.getFullUser();
+        if (user == null || !user.containsSession(session)) {
+            Log.d(TAG, "Unknown session changed playback state. Ignoring.");
+            return;
+        }
+        user.onPlaybackStateChanged(session, promotePriority);
+    }
+
+
+    static boolean isMediaSessionKey(int keyCode) {
+        switch (keyCode) {
+            case KeyEvent.KEYCODE_MEDIA_PLAY:
+            case KeyEvent.KEYCODE_MEDIA_PAUSE:
+            case KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE:
+            case KeyEvent.KEYCODE_MUTE:
+            case KeyEvent.KEYCODE_HEADSETHOOK:
+            case KeyEvent.KEYCODE_MEDIA_STOP:
+            case KeyEvent.KEYCODE_MEDIA_NEXT:
+            case KeyEvent.KEYCODE_MEDIA_PREVIOUS:
+            case KeyEvent.KEYCODE_MEDIA_REWIND:
+            case KeyEvent.KEYCODE_MEDIA_RECORD:
+            case KeyEvent.KEYCODE_MEDIA_FAST_FORWARD:
+                return true;
+        }
+        return false;
+    }
+
     private class Stub extends IMediaCommunicationService.Stub {
         @Override
         public void notifySession2Created(Session2Token sessionToken) {
@@ -344,7 +386,7 @@ public class MediaCommunicationService extends SystemService {
             try {
                 // Check that they can make calls on behalf of the user and get the final user id
                 int resolvedUserId = handleIncomingUser(pid, uid, userId, null);
-                List<Session2Token> result;
+                ArrayList<Session2Token> result;
                 synchronized (mLock) {
                     result = getSession2TokensLocked(resolvedUserId);
                 }
@@ -357,6 +399,25 @@ public class MediaCommunicationService extends SystemService {
         }
 
         @Override
+        public void dispatchMediaKeyEvent(String packageName, KeyEvent keyEvent,
+                boolean asSystemService) {
+            if (keyEvent == null || !isMediaSessionKey(keyEvent.getKeyCode())) {
+                Log.w(TAG, "Attempted to dispatch null or non-media key event.");
+                return;
+            }
+
+            final int pid = Binder.getCallingPid();
+            final int uid = Binder.getCallingUid();
+            final long token = Binder.clearCallingIdentity();
+            try {
+                //TODO: Dispatch key event to media session 2 if required
+                mSessionManager.dispatchMediaKeyEvent(keyEvent, asSystemService);
+            } finally {
+                Binder.restoreCallingIdentity(token);
+            }
+        }
+
+        @Override
         public void registerCallback(IMediaCommunicationServiceCallback callback,
                 String packageName) throws RemoteException {
             Objects.requireNonNull(callback, "callback should not be null");
@@ -475,26 +536,20 @@ public class MediaCommunicationService extends SystemService {
 
     final class FullUserRecord {
         private final int mFullUserId;
-        private final Object mUserLock = new Object();
-        @GuardedBy("mUserLock")
-        private final List<Session2Record> mSessionRecords = new ArrayList<>();
+        private final SessionPriorityList mSessionPriorityList = new SessionPriorityList();
 
         FullUserRecord(int fullUserId) {
             mFullUserId = fullUserId;
         }
 
         public void addSession(Session2Record record) {
-            synchronized (mUserLock) {
-                mSessionRecords.add(record);
-            }
+            mSessionPriorityList.addSession(record);
             mHandler.post(() -> dispatchSession2Created(record.mSessionToken));
             mHandler.post(() -> dispatchSession2Changed(mFullUserId));
         }
 
         private void removeSession(Session2Record record) {
-            synchronized (mUserLock) {
-                mSessionRecords.remove(record);
-            }
+            mSessionPriorityList.removeSession(record);
             mHandler.post(() -> dispatchSession2Changed(mFullUserId));
             //TODO: Handle if the removed session was the media button session.
         }
@@ -504,48 +559,31 @@ public class MediaCommunicationService extends SystemService {
         }
 
         public List<Session2Token> getAllSession2Tokens() {
-            synchronized (mUserLock) {
-                return mSessionRecords.stream()
-                        .map(Session2Record::getSessionToken)
-                        .collect(Collectors.toList());
-            }
+            return mSessionPriorityList.getAllTokens();
         }
 
         public List<Session2Token> getSession2Tokens(int userId) {
-            synchronized (mUserLock) {
-                return mSessionRecords.stream()
-                        .filter(record -> record.getUserId() == userId)
-                        .map(Session2Record::getSessionToken)
-                        .collect(Collectors.toList());
-            }
+            return mSessionPriorityList.getTokensByUserId(userId);
         }
 
         public void destroyAllSessions() {
-            synchronized (mUserLock) {
-                for (Session2Record session : mSessionRecords) {
-                    session.close();
-                }
-                mSessionRecords.clear();
-            }
+            mSessionPriorityList.destroyAllSessions();
             mHandler.post(() -> dispatchSession2Changed(mFullUserId));
         }
 
         public void destroySessionsForUser(int userId) {
-            boolean changed = false;
-            synchronized (mUserLock) {
-                for (int i = mSessionRecords.size() - 1; i >= 0; i--) {
-                    Session2Record session = mSessionRecords.get(i);
-                    if (session.getUserId() == userId) {
-                        mSessionRecords.remove(i);
-                        session.close();
-                        changed = true;
-                    }
-                }
-            }
-            if (changed) {
+            if (mSessionPriorityList.destroySessionsByUserId(userId)) {
                 mHandler.post(() -> dispatchSession2Changed(mFullUserId));
             }
         }
+
+        public boolean containsSession(Session2Record session) {
+            return mSessionPriorityList.contains(session);
+        }
+
+        public void onPlaybackStateChanged(Session2Record session, boolean promotePriority) {
+            mSessionPriorityList.onPlaybackStateChanged(session, promotePriority);
+        }
     }
 
     static final class Session2Record {
@@ -561,6 +599,7 @@ public class MediaCommunicationService extends SystemService {
         @GuardedBy("mSession2RecordLock")
         private boolean mIsClosed;
 
+        //TODO: introduce policy (See MediaSessionPolicyProvider)
         Session2Record(MediaCommunicationService service, FullUserRecord fullUser,
                 Session2Token token, Executor controllerExecutor) {
             mServiceRef = new WeakReference<>(service);
@@ -596,6 +635,12 @@ public class MediaCommunicationService extends SystemService {
             return mSessionToken;
         }
 
+        public boolean checkPlaybackActiveState(boolean expected) {
+            synchronized (mSession2RecordLock) {
+                return mIsConnected && mController.isPlaybackActive() == expected;
+            }
+        }
+
         private class Controller2Callback extends MediaController2.ControllerCallback {
             @Override
             public void onConnected(MediaController2 controller,
@@ -621,6 +666,20 @@ public class MediaCommunicationService extends SystemService {
                     service.onSessionDied(Session2Record.this);
                 }
             }
+
+            @Override
+            public void onPlaybackActiveChanged(
+                    @NonNull MediaController2 controller,
+                    boolean playbackActive) {
+                if (DEBUG) {
+                    Log.d(TAG, "playback active changed, " + mSessionToken + ", active="
+                            + playbackActive);
+                }
+                MediaCommunicationService service = mServiceRef.get();
+                if (service != null) {
+                    service.onSessionPlaybackStateChanged(Session2Record.this, playbackActive);
+                }
+            }
         }
     }
 }
diff --git a/apex/service/java/com/android/server/media/SessionPriorityList.java b/apex/service/java/com/android/server/media/SessionPriorityList.java
new file mode 100644
index 0000000..8145861
--- /dev/null
+++ b/apex/service/java/com/android/server/media/SessionPriorityList.java
@@ -0,0 +1,199 @@
+/*
+ * Copyright 2021 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.server.media;
+
+import android.annotation.Nullable;
+import android.media.Session2Token;
+import android.os.Build;
+import android.util.Log;
+
+import androidx.annotation.RequiresApi;
+
+import com.android.internal.annotations.GuardedBy;
+import com.android.modules.annotation.MinSdk;
+import com.android.server.media.MediaCommunicationService.Session2Record;
+
+import java.util.ArrayList;
+import java.util.List;
+
+//TODO: Define the priority specifically.
+/**
+ * Keeps track of media sessions and their priority for notifications, media
+ * button dispatch, etc.
+ * Higher priority session has more chance to be selected as media button session,
+ * which receives the media button events.
+ */
+@MinSdk(Build.VERSION_CODES.S)
+@RequiresApi(Build.VERSION_CODES.S)
+class SessionPriorityList {
+    private static final String TAG = "SessionPriorityList";
+    private final Object mLock = new Object();
+
+    @GuardedBy("mLock")
+    private final List<Session2Record> mSessions = new ArrayList<>();
+
+    @Nullable
+    private Session2Record mMediaButtonSession;
+    @Nullable
+    private Session2Record mCachedVolumeSession;
+
+    //TODO: integrate AudioPlayerStateMonitor
+
+    public void addSession(Session2Record record) {
+        synchronized (mLock) {
+            mSessions.add(record);
+        }
+    }
+
+    public void removeSession(Session2Record record) {
+        synchronized (mLock) {
+            mSessions.remove(record);
+        }
+        if (record == mMediaButtonSession) {
+            updateMediaButtonSession(null);
+        }
+    }
+
+    public void destroyAllSessions() {
+        synchronized (mLock) {
+            for (Session2Record session : mSessions) {
+                session.close();
+            }
+            mSessions.clear();
+        }
+    }
+
+    public boolean destroySessionsByUserId(int userId) {
+        boolean changed = false;
+        synchronized (mLock) {
+            for (int i = mSessions.size() - 1; i >= 0; i--) {
+                Session2Record session = mSessions.get(i);
+                if (session.getUserId() == userId) {
+                    mSessions.remove(i);
+                    session.close();
+                    changed = true;
+                }
+            }
+        }
+        return changed;
+    }
+
+    public List<Session2Token> getAllTokens() {
+        List<Session2Token> sessions = new ArrayList<>();
+        synchronized (mLock) {
+            for (Session2Record session : mSessions) {
+                sessions.add(session.getSessionToken());
+            }
+        }
+        return sessions;
+    }
+
+    public List<Session2Token> getTokensByUserId(int userId) {
+        List<Session2Token> sessions = new ArrayList<>();
+        synchronized (mLock) {
+            for (Session2Record session : mSessions) {
+                if (session.getUserId() == userId) {
+                    sessions.add(session.getSessionToken());
+                }
+            }
+        }
+        return sessions;
+    }
+
+    /** Gets the media button session which receives the media button events. */
+    @Nullable
+    public Session2Record getMediaButtonSession() {
+        return mMediaButtonSession;
+    }
+
+    /** Gets the media volume session which receives the volume key events. */
+    @Nullable
+    public Session2Record getMediaVolumeSession() {
+        //TODO: if null, calculate it.
+        return mCachedVolumeSession;
+    }
+
+    public boolean contains(Session2Record session) {
+        synchronized (mLock) {
+            return mSessions.contains(session);
+        }
+    }
+
+    public void onPlaybackStateChanged(Session2Record session, boolean promotePriority) {
+        if (promotePriority) {
+            synchronized (mLock) {
+                if (mSessions.remove(session)) {
+                    mSessions.add(0, session);
+                } else {
+                    Log.w(TAG, "onPlaybackStateChanged: Ignoring unknown session");
+                    return;
+                }
+            }
+        } else if (session.checkPlaybackActiveState(false)) {
+            // Just clear the cached volume session when a state goes inactive
+            mCachedVolumeSession = null;
+        }
+
+        // In most cases, playback state isn't needed for finding the media button session,
+        // but we only use it as a hint if an app has multiple local media sessions.
+        // In that case, we pick the media session whose PlaybackState matches
+        // the audio playback configuration.
+        if (mMediaButtonSession != null
+                && mMediaButtonSession.getSessionToken().getUid()
+                == session.getSessionToken().getUid()) {
+            Session2Record newMediaButtonSession =
+                    findMediaButtonSession(mMediaButtonSession.getSessionToken().getUid());
+            if (newMediaButtonSession != mMediaButtonSession) {
+                // Check if the policy states that this session should not be updated as a media
+                // button session.
+                updateMediaButtonSession(newMediaButtonSession);
+            }
+        }
+    }
+
+    private void updateMediaButtonSession(@Nullable Session2Record newSession) {
+        mMediaButtonSession = newSession;
+        //TODO: invoke callbacks for media button session changed listeners
+    }
+
+    /**
+     * Finds the media button session with the given {@param uid}.
+     * If the app has multiple media sessions, the media session whose playback state is not null
+     * and matches the audio playback state becomes the media button session. Otherwise the top
+     * priority session becomes the media button session.
+     *
+     * @return The media button session. Returns {@code null} if the app doesn't have a media
+     *   session.
+     */
+    @Nullable
+    private Session2Record findMediaButtonSession(int uid) {
+        Session2Record mediaButtonSession = null;
+        synchronized (mLock) {
+            for (Session2Record session : mSessions) {
+                if (uid != session.getSessionToken().getUid()) {
+                    continue;
+                }
+                // TODO: check audio player state monitor
+                if (mediaButtonSession == null) {
+                    // Pick the top priority session as a default.
+                    mediaButtonSession = session;
+                }
+            }
+        }
+        return mediaButtonSession;
+    }
+}
diff --git a/apex/service/lint-baseline.xml b/apex/service/lint-baseline.xml
new file mode 100644
index 0000000..def6baf
--- /dev/null
+++ b/apex/service/lint-baseline.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<issues format="6" by="lint 7.2.0-dev" type="baseline" client="" dependencies="true" name="" variant="all" version="7.2.0-dev">
+
+</issues>