[Android] Stop hiding the RWHV layer subtree when hiding the widget

ui/android/window_android.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_ANDROID_WINDOW_ANDROID_H_
 #define UI_ANDROID_WINDOW_ANDROID_H_
 
 #include <jni.h>
 #include <vector>
 
@@ skipping 25 matching lines @@
   void set_content_offset(const gfx::Vector2dF& content_offset) {
     content_offset_ = content_offset;
   }
 
   gfx::Vector2dF content_offset() const {
     return content_offset_;
   }
 
   // Compositor callback relay.
   void OnCompositingDidCommit();
+  void OnVisibilityChanged(bool visible);
 
   void AttachCompositor(WindowAndroidCompositor* compositor);
   void DetachCompositor();
 
   void AddObserver(WindowAndroidObserver* observer);
   void RemoveObserver(WindowAndroidObserver* observer);
 
   WindowAndroidCompositor* GetCompositor() { return compositor_; }
 
   void RequestVSyncUpdate();
   void SetNeedsAnimate();
   void OnVSync(JNIEnv* env,
                jobject obj,
                jlong time_micros,
                jlong period_micros);
   void Animate(base::TimeTicks begin_frame_time);
+  void OnActivityPaused(JNIEnv* env, jobject obj);
+  void OnActivityResumed(JNIEnv* env, jobject obj);
 
  private:
   ~WindowAndroid();
 
   base::android::ScopedJavaGlobalRef<jobject> java_window_;
   gfx::Vector2dF content_offset_;
   WindowAndroidCompositor* compositor_;
 
   ObserverList<WindowAndroidObserver> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowAndroid);
 };
 
 }  // namespace ui
 
 #endif  // UI_ANDROID_WINDOW_ANDROID_H_