Move the WindowInsetsAnimation.Callback implementation to an inner cl…

…ass to avoid Android class loader warnings

ImeSyncDeferringInsetsCallback had been a subclass of WindowInsetsAnimation.Callback,
which was introduced in Android API level 30.  The class loader on
older versions of Android was logging warnings about unresolvable
classes when loading TextInputPlugin, which holds a reference to
ImeSyncDeferringInsetsCallback.

See flutter/flutter#66908

shell/platform/android/io/flutter/plugin/editing/ImeSyncDeferringInsetsCallback.java

@@ -46,13 +46,15 @@
 @RequiresApi(30)
 @SuppressLint({"NewApi", "Override"})
 @Keep
-class ImeSyncDeferringInsetsCallback extends WindowInsetsAnimation.Callback
-    implements View.OnApplyWindowInsetsListener {
+class ImeSyncDeferringInsetsCallback {
   private int overlayInsetTypes;
   private int deferredInsetTypes;
 
   private View view;
   private WindowInsets lastWindowInsets;
+  private AnimationCallback animationCallback;
+  private InsetsListener insetsListener;
+
   // True when an animation that matches deferredInsetTypes is active.
   //
   // While this is active, this class will capture the initial window inset
@@ -67,16 +69,17 @@ class ImeSyncDeferringInsetsCallback extends WindowInsetsAnimation.Callback
 
   ImeSyncDeferringInsetsCallback(
       @NonNull View view, int overlayInsetTypes, int deferredInsetTypes) {
-    super(WindowInsetsAnimation.Callback.DISPATCH_MODE_CONTINUE_ON_SUBTREE);
     this.overlayInsetTypes = overlayInsetTypes;
     this.deferredInsetTypes = deferredInsetTypes;
     this.view = view;
   }
 
   // Add this object's event listeners to its view.
   void install() {
-    view.setWindowInsetsAnimationCallback(this);
-    view.setOnApplyWindowInsetsListener(this);
+    animationCallback = new AnimationCallback();
+    insetsListener = new InsetsListener();
+    view.setWindowInsetsAnimationCallback(animationCallback);
+    view.setOnApplyWindowInsetsListener(insetsListener);
   }
 
   // Remove this object's event listeners from its view.
@@ -85,7 +88,48 @@ void remove() {
     view.setOnApplyWindowInsetsListener(null);
   }
 
-  @Override
+  @VisibleForTesting
+  View.OnApplyWindowInsetsListener getInsetsListener() {
+    return insetsListener;
+  }
+
+  @VisibleForTesting
+  WindowInsetsAnimation.Callback getAnimationCallback() {
+    return animationCallback;
+  }
+
+  // WindowInsetsAnimation.Callback was introduced in API level 30.  The callback
+  // subclass is separated into an inner class in order to avoid warnings from
+  // the Android class loader on older platforms.
+  private class AnimationCallback extends WindowInsetsAnimation.Callback {
+    AnimationCallback() {
+      super(WindowInsetsAnimation.Callback.DISPATCH_MODE_CONTINUE_ON_SUBTREE);
+    }
+
+    @Override
+    public void onPrepare(WindowInsetsAnimation animation) {
+      ImeSyncDeferringInsetsCallback.this.onPrepare(animation);
+    }
+
+    @Override
+    public WindowInsets onProgress(
+        WindowInsets insets, List<WindowInsetsAnimation> runningAnimations) {
+      return ImeSyncDeferringInsetsCallback.this.onProgress(insets, runningAnimations);
+    }
+
+    @Override
+    public void onEnd(WindowInsetsAnimation animation) {
+      ImeSyncDeferringInsetsCallback.this.onEnd(animation);
+    }
+  }
+
+  private class InsetsListener implements View.OnApplyWindowInsetsListener {
+    @Override
+    public WindowInsets onApplyWindowInsets(View view, WindowInsets windowInsets) {
+      return ImeSyncDeferringInsetsCallback.this.onApplyWindowInsets(view, windowInsets);
+    }
+  }
+
   public WindowInsets onApplyWindowInsets(View view, WindowInsets windowInsets) {
     this.view = view;
     if (needsSave) {
@@ -108,15 +152,13 @@ public WindowInsets onApplyWindowInsets(View view, WindowInsets windowInsets) {
     return view.onApplyWindowInsets(windowInsets);
   }
 
-  @Override
   public void onPrepare(WindowInsetsAnimation animation) {
     if ((animation.getTypeMask() & deferredInsetTypes) != 0) {
       animating = true;
       needsSave = true;
     }
   }
 
-  @Override
   public WindowInsets onProgress(
       WindowInsets insets, List<WindowInsetsAnimation> runningAnimations) {
     if (!animating || needsSave) {
@@ -158,7 +200,6 @@ public WindowInsets onProgress(
     return insets;
   }
 
-  @Override
   public void onEnd(WindowInsetsAnimation animation) {
     if (animating && (animation.getTypeMask() & deferredInsetTypes) != 0) {
       // If we deferred the IME insets and an IME animation has finished, we need to reset

shell/platform/android/test/io/flutter/plugin/editing/TextInputPluginTest.java

@@ -1076,9 +1076,9 @@ public void ime_windowInsetsSync() {
     assertEquals(0, viewportMetricsCaptor.getValue().viewInsetBottom);
     assertEquals(0, viewportMetricsCaptor.getValue().viewInsetTop);
 
-    imeSyncCallback.onPrepare(animation);
-    imeSyncCallback.onApplyWindowInsets(testView, deferredInsets);
-    imeSyncCallback.onStart(animation, null);
+    imeSyncCallback.getAnimationCallback().onPrepare(animation);
+    imeSyncCallback.getInsetsListener().onApplyWindowInsets(testView, deferredInsets);
+    imeSyncCallback.getAnimationCallback().onStart(animation, null);
     // Only the final state call is saved, extra calls are passed on.
     imeSyncCallback.onApplyWindowInsets(testView, imeInsets2);
 
@@ -1089,23 +1089,23 @@ public void ime_windowInsetsSync() {
     assertEquals(0, viewportMetricsCaptor.getValue().viewInsetBottom);
     assertEquals(0, viewportMetricsCaptor.getValue().viewInsetTop);
 
-    imeSyncCallback.onProgress(imeInsets0, animationList);
+    imeSyncCallback.getAnimationCallback().onProgress(imeInsets0, animationList);
 
     verify(flutterRenderer).setViewportMetrics(viewportMetricsCaptor.capture());
     assertEquals(40, viewportMetricsCaptor.getValue().viewPaddingBottom);
     assertEquals(10, viewportMetricsCaptor.getValue().viewPaddingTop);
     assertEquals(60, viewportMetricsCaptor.getValue().viewInsetBottom);
     assertEquals(0, viewportMetricsCaptor.getValue().viewInsetTop);
 
-    imeSyncCallback.onProgress(imeInsets1, animationList);
+    imeSyncCallback.getAnimationCallback().onProgress(imeInsets1, animationList);
 
     verify(flutterRenderer).setViewportMetrics(viewportMetricsCaptor.capture());
     assertEquals(40, viewportMetricsCaptor.getValue().viewPaddingBottom);
     assertEquals(10, viewportMetricsCaptor.getValue().viewPaddingTop);
     assertEquals(0, viewportMetricsCaptor.getValue().viewInsetBottom); // Cannot be negative
     assertEquals(0, viewportMetricsCaptor.getValue().viewInsetTop);
 
-    imeSyncCallback.onEnd(animation);
+    imeSyncCallback.getAnimationCallback().onEnd(animation);
 
     verify(flutterRenderer).setViewportMetrics(viewportMetricsCaptor.capture());
     // Values should be of deferredInsets, not imeInsets2