Fix the crash when applying daily wallpaper without network connection

It's because CustomizationPickerActivity is cast to BaseActivity to call isSafeToCommitFragmentTransaction(), but it is not a BaseActivity.
Extract isSafeToCommitFragmentTransaction() to an interface to let CustomizationPickerActivity to implement it.

Bug: 167943713
Change-Id: I497620f86f5309392761ce11e19bc183a70178cb

3 files changed, 33 insertions, 2 deletions

diff --git a/src/com/android/wallpaper/picker/BaseActivity.java b/src/com/android/wallpaper/picker/BaseActivity.java
index 7f2ea604..25a2b2ac 100755
--- a/src/com/android/wallpaper/picker/BaseActivity.java
+++ b/src/com/android/wallpaper/picker/BaseActivity.java
@@ -21,7 +21,7 @@ import androidx.appcompat.app.AppCompatActivity;
  * Base activity that keeps track of whether fragment transactions are safe to commit given the
  * activity's current lifecycle state.
  */
-public class BaseActivity extends AppCompatActivity {
+public class BaseActivity extends AppCompatActivity implements FragmentTransactionChecker {
 
     private boolean mIsSafeToCommitFragmentTransaction;
 
@@ -37,6 +37,7 @@ public class BaseActivity extends AppCompatActivity {
         mIsSafeToCommitFragmentTransaction = false;
     }
 
+    @Override
     public boolean isSafeToCommitFragmentTransaction() {
         return mIsSafeToCommitFragmentTransaction;
     }
diff --git a/src/com/android/wallpaper/picker/FragmentTransactionChecker.java b/src/com/android/wallpaper/picker/FragmentTransactionChecker.java
new file mode 100644
index 00000000..c25a41ff
--- /dev/null
+++ b/src/com/android/wallpaper/picker/FragmentTransactionChecker.java
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2020 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.wallpaper.picker;
+
+/**
+ * An interface for a class to keep track of whether fragment transactions are safe to commit given
+ * the activity's current lifecycle state.
+ */
+public interface FragmentTransactionChecker {
+    /**
+     * Checks if the fragment transactions are safe to commit
+     *
+     * @return {@code true} if it is safe; {@code false} otherwise.
+     */
+    boolean isSafeToCommitFragmentTransaction();
+}
diff --git a/src/com/android/wallpaper/picker/individual/IndividualPickerFragment.java b/src/com/android/wallpaper/picker/individual/IndividualPickerFragment.java
index 5fd0e7ac..260d121f 100755
--- a/src/com/android/wallpaper/picker/individual/IndividualPickerFragment.java
+++ b/src/com/android/wallpaper/picker/individual/IndividualPickerFragment.java
@@ -78,6 +78,7 @@ import com.android.wallpaper.module.WallpaperSetter;
 import com.android.wallpaper.picker.BaseActivity;
 import com.android.wallpaper.picker.BottomActionBarFragment;
 import com.android.wallpaper.picker.CurrentWallpaperBottomSheetPresenter;
+import com.android.wallpaper.picker.FragmentTransactionChecker;
 import com.android.wallpaper.picker.MyPhotosStarter.MyPhotosStarterProvider;
 import com.android.wallpaper.picker.PreviewActivity;
 import com.android.wallpaper.picker.RotationStarter;
@@ -816,7 +817,7 @@ public class IndividualPickerFragment extends BottomActionBarFragment
     }
 
     private void showStartRotationErrorDialog(@NetworkPreference int networkPreference) {
-        BaseActivity activity = (BaseActivity) getActivity();
+        FragmentTransactionChecker activity = (FragmentTransactionChecker) getActivity();
         if (activity != null) {
             StartRotationErrorDialogFragment startRotationErrorDialogFragment =
                     StartRotationErrorDialogFragment.newInstance(networkPreference);