Revert "Call Shell::NotifyLowMemoryWarning on Android Trim and LowMemory events (#18979)" (#19023)

This reverts commit f5ab179e.

shell/platform/android/android_shell_holder.cc

@@ -181,8 +181,4 @@ fml::WeakPtr<PlatformViewAndroid> AndroidShellHolder::GetPlatformView() {
   return platform_view_;
 }
 
-void AndroidShellHolder::NotifyLowMemoryWarning() {
-  FML_DCHECK(shell_);
-  shell_->NotifyLowMemoryWarning();
-}
 }  // namespace flutter

shell/platform/android/android_shell_holder.h

@@ -40,8 +40,6 @@ class AndroidShellHolder {
 
   void UpdateAssetManager(fml::RefPtr<flutter::AssetManager> asset_manager);
 
-  void NotifyLowMemoryWarning();
-
  private:
   const flutter::Settings settings_;
   const std::shared_ptr<PlatformViewAndroidJNI> jni_facade_;

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

@@ -629,9 +629,6 @@ import java.util.Arrays;
   void onTrimMemory(int level) {
     ensureAlive();
     if (flutterEngine != null) {
-      // This is always an indication that the Dart VM should collect memory
-      // and free any unneeded resources.
-      flutterEngine.getDartExecutor().notifyLowMemoryWarning();
       // Use a trim level delivered while the application is running so the
       // framework has a chance to react to the notification.
       if (level == TRIM_MEMORY_RUNNING_LOW) {
@@ -654,7 +651,6 @@ import java.util.Arrays;
   void onLowMemory() {
     Log.v(TAG, "Forwarding onLowMemory() to FlutterEngine.");
     ensureAlive();
-    flutterEngine.getDartExecutor().notifyLowMemoryWarning();
     flutterEngine.getSystemChannel().sendMemoryPressureWarning();
   }
 

shell/platform/android/io/flutter/embedding/engine/FlutterJNI.java

@@ -834,22 +834,6 @@ public class FlutterJNI {
   // TODO(mattcarroll): determine if this is nonull or nullable
   private native Bitmap nativeGetBitmap(long nativePlatformViewId);
 
-  /**
-   * Notifies the Dart VM of a low memory event, or that the application is in a state such that now
-   * is an appropriate time to free resources, such as going to the background.
-   *
-   * <p>This is distinct from sending a SystemChannel message about low memory, which only notifies
-   * the running Flutter application.
-   */
-  @UiThread
-  public void notifyLowMemoryWarning() {
-    ensureRunningOnMainThread();
-    ensureAttachedToNative();
-    nativeNotifyLowMemoryWarning();
-  }
-
-  private native void nativeNotifyLowMemoryWarning();
-
   private void ensureRunningOnMainThread() {
     if (Looper.myLooper() != mainLooper) {
       throw new RuntimeException(

shell/platform/android/io/flutter/embedding/engine/dart/DartExecutor.java

@@ -232,19 +232,6 @@ public class DartExecutor implements BinaryMessenger {
     }
   }
 
-  /**
-   * Notify the Dart VM of a low memory event, or that the application is in a state such that now
-   * is an appropriate time to free resources, such as going to the background.
-   *
-   * <p>This does not notify a Flutter application about memory pressure. For that, use the {@link
-   * SystemChannel#sendMemoryPressureWarning}.
-   */
-  public void notifyLowMemoryWarning() {
-    if (flutterJNI.isAttached()) {
-      flutterJNI.notifyLowMemoryWarning();
-    }
-  }
-
   /**
    * Configuration options that specify which Dart entrypoint function is executed and where to find
    * that entrypoint and other assets required for Dart execution.

shell/platform/android/io/flutter/view/FlutterView.java

@@ -320,7 +320,6 @@ public class FlutterView extends SurfaceView
   }
 
   public void onMemoryPressure() {
-    mNativeView.getFlutterJNI().notifyLowMemoryWarning();
     systemChannel.sendMemoryPressureWarning();
   }
 

shell/platform/android/platform_view_android_jni_impl.cc

@@ -436,12 +436,6 @@ static void InvokePlatformMessageEmptyResponseCallback(JNIEnv* env,
       );
 }
 
-static void NotifyLowMemoryWarning(JNIEnv* env,
-                                   jobject obj,
-                                   jlong shell_holder) {
-  ANDROID_SHELL_HOLDER->NotifyLowMemoryWarning();
-}
-
 static jboolean FlutterTextUtilsIsEmoji(JNIEnv* env,
                                         jobject obj,
                                         jint codePoint) {
@@ -512,11 +506,6 @@ bool RegisterApi(JNIEnv* env) {
           .fnPtr = reinterpret_cast<void*>(
               &InvokePlatformMessageEmptyResponseCallback),
       },
-      {
-          .name = "nativeNotifyLowMemoryWarning",
-          .signature = "()V",
-          .fnPtr = reinterpret_cast<void*>(&NotifyLowMemoryWarning),
-      },
 
       // Start of methods from FlutterView
       {

shell/platform/android/test/io/flutter/embedding/android/FlutterActivityAndFragmentDelegateTest.java

 package io.flutter.embedding.android;
 
-import static android.content.ComponentCallbacks2.*;
+import static android.content.ComponentCallbacks2.TRIM_MEMORY_RUNNING_LOW;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 import static org.mockito.Matchers.any;
@@ -442,7 +442,7 @@ public class FlutterActivityAndFragmentDelegateTest {
   }
 
   @Test
-  public void itNotifiesDartExecutorAndSendsMessageOverSystemChannelWhenToldToTrimMemory() {
+  public void itSendsMessageOverSystemChannelWhenToldToTrimMemory() {
     // Create the real object that we're testing.
     FlutterActivityAndFragmentDelegate delegate = new FlutterActivityAndFragmentDelegate(mockHost);
 
@@ -451,21 +451,14 @@ public class FlutterActivityAndFragmentDelegateTest {
     delegate.onAttach(RuntimeEnvironment.application);
 
     // Emulate the host and call the method that we expect to be forwarded.
-    delegate.onTrimMemory(TRIM_MEMORY_RUNNING_MODERATE);
     delegate.onTrimMemory(TRIM_MEMORY_RUNNING_LOW);
-    delegate.onTrimMemory(TRIM_MEMORY_RUNNING_CRITICAL);
-    delegate.onTrimMemory(TRIM_MEMORY_BACKGROUND);
-    delegate.onTrimMemory(TRIM_MEMORY_COMPLETE);
-    delegate.onTrimMemory(TRIM_MEMORY_MODERATE);
-    delegate.onTrimMemory(TRIM_MEMORY_UI_HIDDEN);
 
     // Verify that the call was forwarded to the engine.
-    verify(mockFlutterEngine.getDartExecutor(), times(7)).notifyLowMemoryWarning();
     verify(mockFlutterEngine.getSystemChannel(), times(1)).sendMemoryPressureWarning();
   }
 
   @Test
-  public void itNotifiesDartExecutorAndSendsMessageOverSystemChannelWhenInformedOfLowMemory() {
+  public void itSendsMessageOverSystemChannelWhenInformedOfLowMemory() {
     // Create the real object that we're testing.
     FlutterActivityAndFragmentDelegate delegate = new FlutterActivityAndFragmentDelegate(mockHost);
 
@@ -477,7 +470,6 @@ public class FlutterActivityAndFragmentDelegateTest {
     delegate.onLowMemory();
 
     // Verify that the call was forwarded to the engine.
-    verify(mockFlutterEngine.getDartExecutor(), times(1)).notifyLowMemoryWarning();
     verify(mockFlutterEngine.getSystemChannel(), times(1)).sendMemoryPressureWarning();
   }
 

shell/platform/android/test/io/flutter/embedding/engine/dart/DartExecutorTest.java

@@ -6,7 +6,6 @@ import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
-import static org.mockito.Mockito.when;
 
 import android.content.res.AssetManager;
 import io.flutter.embedding.engine.FlutterJNI;
@@ -39,14 +38,4 @@ public class DartExecutorTest {
     verify(fakeFlutterJni, times(1))
         .dispatchPlatformMessage(eq("fake_channel"), eq(fakeMessage), anyInt(), anyInt());
   }
-
-  @Test
-  public void itNotifiesLowMemoryWarning() {
-    FlutterJNI mockFlutterJNI = mock(FlutterJNI.class);
-    when(mockFlutterJNI.isAttached()).thenReturn(true);
-
-    DartExecutor dartExecutor = new DartExecutor(mockFlutterJNI, mock(AssetManager.class));
-    dartExecutor.notifyLowMemoryWarning();
-    verify(mockFlutterJNI, times(1)).notifyLowMemoryWarning();
-  }
 }