Export |ExclusiveAppComponent<Activity>| from FlutterActivity/FlutterFragment class (flutter/engine#30864)

engine/src/flutter/shell/platform/android/io/flutter/embedding/android/FlutterActivity.java

@@ -450,6 +450,15 @@ public class FlutterActivity extends Activity
     this.delegate = delegate;
   }
 
+  /**
+   * Returns the Android App Component exclusively attached to {@link
+   * io.flutter.embedding.engine.FlutterEngine}.
+   */
+  @Override
+  public ExclusiveAppComponent<Activity> getExclusiveAppComponent() {
+    return delegate;
+  }
+
   @Override
   protected void onCreate(@Nullable Bundle savedInstanceState) {
     switchLaunchThemeForNormalTheme();

engine/src/flutter/shell/platform/android/io/flutter/embedding/android/FlutterActivityAndFragmentDelegate.java

@@ -953,6 +953,20 @@ import java.util.Arrays;
     @NonNull
     TransparencyMode getTransparencyMode();
 
+    /**
+     * Returns the {@link ExclusiveAppComponent<Activity>} that is associated with {@link
+     * io.flutter.embedding.engine.FlutterEngine}.
+     *
+     * <p>In the scenario where multiple {@link FlutterActivity} or {@link FlutterFragment} share
+     * the same {@link FlutterEngine}, to attach/re-attache a {@link FlutterActivity} or {@link
+     * FlutterFragment} to the shared {@link FlutterEngine}, we MUST manually invoke {@link
+     * ActivityControlSurface#attachToActivity(ExclusiveAppComponent, Lifecycle)}.
+     *
+     * <p>The {@link ExclusiveAppComponent} is exposed here so that subclasses of {@link
+     * FlutterActivity} or {@link FlutterFragment} can access it.
+     */
+    ExclusiveAppComponent<Activity> getExclusiveAppComponent();
+
     @Nullable
     SplashScreen provideSplashScreen();
 

engine/src/flutter/shell/platform/android/io/flutter/embedding/android/FlutterFragment.java

@@ -746,6 +746,15 @@ public class FlutterFragment extends Fragment
     this.delegate = delegate;
   }
 
+  /**
+   * Returns the Android App Component exclusively attached to {@link
+   * io.flutter.embedding.engine.FlutterEngine}.
+   */
+  @Override
+  public ExclusiveAppComponent<Activity> getExclusiveAppComponent() {
+    return delegate;
+  }
+
   @Override
   public void onAttach(@NonNull Context context) {
     super.onAttach(context);

engine/src/flutter/shell/platform/android/test/io/flutter/embedding/android/FlutterActivityTest.java

@@ -304,6 +304,19 @@ public class FlutterActivityTest {
     verify(mockDelegate, times(1)).release();
   }
 
+  @Test
+  public void itReturnsExclusiveAppComponent() {
+    Intent intent = FlutterActivity.createDefaultIntent(RuntimeEnvironment.application);
+    ActivityController<FlutterActivity> activityController =
+        Robolectric.buildActivity(FlutterActivity.class, intent);
+    FlutterActivity flutterActivity = activityController.get();
+    FlutterActivityAndFragmentDelegate delegate =
+        new FlutterActivityAndFragmentDelegate(flutterActivity);
+    flutterActivity.setDelegate(delegate);
+
+    assertEquals(flutterActivity.getExclusiveAppComponent(), delegate);
+  }
+
   @Test
   public void itDelaysDrawing() {
     Intent intent = FlutterActivity.createDefaultIntent(RuntimeEnvironment.application);

engine/src/flutter/shell/platform/android/test/io/flutter/embedding/android/FlutterAndroidComponentTest.java

@@ -335,6 +335,11 @@ public class FlutterAndroidComponentTest {
       return TransparencyMode.transparent;
     }
 
+    @Override
+    public ExclusiveAppComponent<Activity> getExclusiveAppComponent() {
+      return null;
+    }
+
     @Nullable
     @Override
     public SplashScreen provideSplashScreen() {

engine/src/flutter/shell/platform/android/test/io/flutter/embedding/android/FlutterFragmentTest.java

@@ -213,6 +213,15 @@ public class FlutterFragmentTest {
     assertFalse(mockDelegate.isAttached());
   }
 
+  @Test
+  public void itReturnsExclusiveAppComponent() {
+    FlutterFragment fragment = FlutterFragment.createDefault();
+    FlutterActivityAndFragmentDelegate delegate = new FlutterActivityAndFragmentDelegate(fragment);
+    fragment.setDelegate(delegate);
+
+    assertEquals(fragment.getExclusiveAppComponent(), delegate);
+  }
+
   @Test
   public void itDelegatesOnBackPressedAutomaticallyWhenEnabled() {
     // We need to mock FlutterJNI to avoid triggering native code.