Revert of [Android] Stop hiding the RWHV layer subtree when hiding the widget (patchset #12 id:330001 of https://codereview.chromium.org/1001573003/)

Reason for revert:
Speculative fix for blank display after cold startup.

Original issue's description:
> Reland "[Android] Preserve the front buffer when the activity is paused"
>
> This change was reverted in r322170 due to WebView breakage. The
> ApplicationStatus dependency has been made optional, allowing
> WebView to opt-out of its use.
>
> Original description: ----------------------------
>
> Currently, when an activity is stopped, we explicitly hide the
> foreground Tab. This is problematic, as current hiding semantics
> might clear the visual front buffer before the window is hidden.
> This in turn causes an unpleasant flickering during activity
> transitions, e.g., when backgrounding Chrome or locking the screen.
>
> Wire Activity onPause/onResume notifications to WindowAndroidObservers,
> allowing the foreground tab to preserve its front buffer while hiding
> its web content. If the tab is explicitly hidden, or the root window
> is lost, the front buffer will be cleared as usual.
>
> BUG=462752,434401
>
> Committed: https://crrev.com/7954daf991a2adda234dc2e886b2d1ddf0049221
> Cr-Commit-Position: refs/heads/master@{#322228}

TBR=sievers@chromium.org,dtrainor@chromium.org,tedchoc@chromium.org,piman@chromium.org,boliu@chromium.org,torne@chromium.org
BUG=481450,481115,434401

Review URL: https://codereview.chromium.org/1109863003

Cr-Commit-Position: refs/heads/master@{#327092}

14 files changed, 64 insertions, 187 deletions

diff --git a/android_webview/java/src/org/chromium/android_webview/AwContents.java b/android_webview/java/src/org/chromium/android_webview/AwContents.java
index 0a0e853..4a97cab 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwContents.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwContents.java
@@ -871,11 +871,9 @@ public class AwContents implements SmartClipProvider,
 
         WebContents webContents = nativeGetWebContents(mNativeAwContents);
 
-        // WebView does not currently initialize ApplicationStatus, crbug.com/470582.
-        final boolean listenToActivityState = false;
         Activity activity = ContentViewCore.activityFromContext(mContext);
         mWindowAndroid = activity != null
-                ? new ActivityWindowAndroid(activity, listenToActivityState)
+                ? new ActivityWindowAndroid(activity)
                 : new WindowAndroid(mContext.getApplicationContext());
         mContentViewCore = createAndInitializeContentViewCore(
                 mContainerView, mContext, mInternalAccessAdapter, webContents,
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/Tab.java b/chrome/android/java/src/org/chromium/chrome/browser/Tab.java
index 5d24d1f6..7806061 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/Tab.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/Tab.java
@@ -1213,6 +1213,13 @@ public class Tab implements ViewGroup.OnHierarchyChangeListener,
     }
 
     /**
+     * Called on the foreground tab when the Activity is stopped.
+     */
+    public void onActivityStop() {
+        hide();
+    }
+
+    /**
      * Prepares the tab to be shown. This method is supposed to be called before the tab is
      * displayed. It restores the ContentView if it is not available after the cold start and
      * reloads the tab if its renderer has crashed.
diff --git a/chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellActivity.java b/chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellActivity.java
index 4e77c83..a3130be 100644
--- a/chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellActivity.java
+++ b/chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellActivity.java
@@ -82,8 +82,7 @@ public class ChromeShellActivity extends AppCompatActivity implements AppMenuPro
             new ActivityWindowAndroidFactory() {
                 @Override
                 public ActivityWindowAndroid getActivityWindowAndroid(Activity activity) {
-                    final boolean listenToActivityState = true;
-                    return new ActivityWindowAndroid(activity, listenToActivityState);
+                    return new ActivityWindowAndroid(activity);
                 }
             };
 
@@ -273,6 +272,9 @@ public class ChromeShellActivity extends AppCompatActivity implements AppMenuPro
         super.onStop();
 
         if (mToolbar != null) mToolbar.hideSuggestions();
+
+        Tab activeTab = getActiveTab();
+        if (activeTab != null) activeTab.onActivityStop();
     }
 
     @Override
diff --git a/content/browser/renderer_host/compositor_impl_android.cc b/content/browser/renderer_host/compositor_impl_android.cc
index 4fe0555..d1c4d01 100644
--- a/content/browser/renderer_host/compositor_impl_android.cc
+++ b/content/browser/renderer_host/compositor_impl_android.cc
@@ -469,7 +469,6 @@ void CompositorImpl::SetVisible(bool visible) {
     CreateLayerTreeHost();
     ui_resource_provider_.SetLayerTreeHost(host_.get());
   }
-  root_window_->OnVisibilityChanged(visible);
 }
 
 void CompositorImpl::setDeviceScaleFactor(float factor) {
diff --git a/content/browser/renderer_host/delegated_frame_evictor.cc b/content/browser/renderer_host/delegated_frame_evictor.cc
index 65ae483..33d6b2c 100644
--- a/content/browser/renderer_host/delegated_frame_evictor.cc
+++ b/content/browser/renderer_host/delegated_frame_evictor.cc
@@ -10,13 +10,11 @@ namespace content {
 
 DelegatedFrameEvictor::DelegatedFrameEvictor(
     DelegatedFrameEvictorClient* client)
-    : client_(client), has_frame_(false), visible_(false) {
-}
+    : client_(client), has_frame_(false) {}
 
 DelegatedFrameEvictor::~DelegatedFrameEvictor() { DiscardedFrame(); }
 
 void DelegatedFrameEvictor::SwappedFrame(bool visible) {
-  visible_ = visible;
   has_frame_ = true;
   RendererFrameManager::GetInstance()->AddFrame(this, visible);
 }
@@ -27,14 +25,11 @@ void DelegatedFrameEvictor::DiscardedFrame() {
 }
 
 void DelegatedFrameEvictor::SetVisible(bool visible) {
-  if (visible_ == visible)
-    return;
-  visible_ = visible;
   if (has_frame_) {
     if (visible) {
-      LockFrame();
+      RendererFrameManager::GetInstance()->LockFrame(this);
     } else {
-      UnlockFrame();
+      RendererFrameManager::GetInstance()->UnlockFrame(this);
     }
   }
 }
diff --git a/content/browser/renderer_host/delegated_frame_evictor.h b/content/browser/renderer_host/delegated_frame_evictor.h
index 9e9f68a..796b6c2 100644
--- a/content/browser/renderer_host/delegated_frame_evictor.h
+++ b/content/browser/renderer_host/delegated_frame_evictor.h
@@ -35,7 +35,6 @@ class CONTENT_EXPORT DelegatedFrameEvictor : public RendererFrameManagerClient {
 
   DelegatedFrameEvictorClient* client_;
   bool has_frame_;
-  bool visible_;
 
   DISALLOW_COPY_AND_ASSIGN(DelegatedFrameEvictor);
 };
diff --git a/content/browser/renderer_host/render_widget_host_view_android.cc b/content/browser/renderer_host/render_widget_host_view_android.cc
index d56bee1..4d76399 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -583,7 +583,23 @@ void RenderWidgetHostViewAndroid::Show() {
     return;
 
   is_showing_ = true;
-  ShowInternal();
+  if (layer_.get())
+    layer_->SetHideLayerAndSubtree(false);
+
+  if (overscroll_controller_)
+    overscroll_controller_->Enable();
+
+  frame_evictor_->SetVisible(true);
+
+  if (!host_ || !host_->is_hidden())
+    return;
+
+  host_->WasShown(ui::LatencyInfo());
+
+  if (content_view_core_) {
+    StartObservingRootWindow();
+    RequestVSyncUpdate(BEGIN_FRAME);
+  }
 }
 
 void RenderWidgetHostViewAndroid::Hide() {
@@ -591,10 +607,27 @@ void RenderWidgetHostViewAndroid::Hide() {
     return;
 
   is_showing_ = false;
+  if (layer_.get() && locks_on_frame_count_ == 0)
+    layer_->SetHideLayerAndSubtree(true);
+
+  if (overscroll_controller_)
+    overscroll_controller_->Disable();
+
+  frame_evictor_->SetVisible(false);
+  // We don't know if we will ever get a frame if we are hiding the renderer, so
+  // we need to cancel all requests
+  AbortPendingReadbackRequests();
+
+  RunAckCallbacks(cc::SurfaceDrawStatus::DRAW_SKIPPED);
+
+  if (!host_ || host_->is_hidden())
+    return;
 
-  bool hide_frontbuffer = true;
-  bool stop_observing_root_window = true;
-  HideInternal(hide_frontbuffer, stop_observing_root_window);
+  // Inform the renderer that we are being hidden so it can reduce its resource
+  // utilization.
+  host_->WasHidden();
+
+  StopObservingRootWindow();
 }
 
 bool RenderWidgetHostViewAndroid::IsShowing() {
@@ -1430,57 +1463,6 @@ void RenderWidgetHostViewAndroid::AcceleratedSurfaceInitialized(int route_id) {
   accelerated_surface_route_id_ = route_id;
 }
 
-void RenderWidgetHostViewAndroid::ShowInternal() {
-  DCHECK(is_showing_);
-  if (!host_ || !host_->is_hidden())
-    return;
-
-  if (layer_.get())
-    layer_->SetHideLayerAndSubtree(false);
-
-  frame_evictor_->SetVisible(true);
-
-  if (overscroll_controller_)
-    overscroll_controller_->Enable();
-
-  host_->WasShown(ui::LatencyInfo());
-
-  if (content_view_core_) {
-    StartObservingRootWindow();
-    RequestVSyncUpdate(BEGIN_FRAME);
-  }
-}
-
-void RenderWidgetHostViewAndroid::HideInternal(
-    bool hide_frontbuffer,
-    bool stop_observing_root_window) {
-  if (hide_frontbuffer) {
-    if (layer_.get() && locks_on_frame_count_ == 0)
-      layer_->SetHideLayerAndSubtree(true);
-
-    frame_evictor_->SetVisible(false);
-  }
-
-  if (stop_observing_root_window)
-    StopObservingRootWindow();
-
-  if (!host_ || host_->is_hidden())
-    return;
-
-  if (overscroll_controller_)
-    overscroll_controller_->Disable();
-
-  // We don't know if we will ever get a frame if we are hiding the renderer, so
-  // we need to cancel all requests
-  AbortPendingReadbackRequests();
-
-  RunAckCallbacks(cc::SurfaceDrawStatus::DRAW_SKIPPED);
-
-  // Inform the renderer that we are being hidden so it can reduce its resource
-  // utilization.
-  host_->WasHidden();
-}
-
 void RenderWidgetHostViewAndroid::AttachLayers() {
   if (!content_view_core_)
     return;
@@ -1508,12 +1490,6 @@ void RenderWidgetHostViewAndroid::RemoveLayers() {
 void RenderWidgetHostViewAndroid::RequestVSyncUpdate(uint32 requests) {
   bool should_request_vsync = !outstanding_vsync_requests_ && requests;
   outstanding_vsync_requests_ |= requests;
-
-  // If the host has been hidden, defer vsync requests until it is shown
-  // again via |Show()|.
-  if (!host_ || host_->is_hidden())
-    return;
-
   // Note that if we're not currently observing the root window, outstanding
   // vsync requests will be pushed if/when we resume observing in
   // |StartObservingRootWindow()|.
@@ -1523,7 +1499,6 @@ void RenderWidgetHostViewAndroid::RequestVSyncUpdate(uint32 requests) {
 
 void RenderWidgetHostViewAndroid::StartObservingRootWindow() {
   DCHECK(content_view_core_);
-  DCHECK(is_showing_);
   if (observing_root_window_)
     return;
 
@@ -1840,8 +1815,7 @@ void RenderWidgetHostViewAndroid::SetContentViewCore(
   if (!content_view_core_)
     return;
 
-  if (is_showing_)
-    StartObservingRootWindow();
+  StartObservingRootWindow();
 
   if (resize)
     WasResized();
@@ -1882,17 +1856,6 @@ void RenderWidgetHostViewAndroid::OnCompositingDidCommit() {
   RunAckCallbacks(cc::SurfaceDrawStatus::DRAWN);
 }
 
-void RenderWidgetHostViewAndroid::OnRootWindowVisibilityChanged(bool visible) {
-  DCHECK(is_showing_);
-  if (visible) {
-    ShowInternal();
-  } else {
-    bool hide_frontbuffer = true;
-    bool stop_observing_root_window = false;
-    HideInternal(hide_frontbuffer, stop_observing_root_window);
-  }
-}
-
 void RenderWidgetHostViewAndroid::OnAttachCompositor() {
   DCHECK(content_view_core_);
   if (!overscroll_controller_)
@@ -1909,7 +1872,7 @@ void RenderWidgetHostViewAndroid::OnDetachCompositor() {
 void RenderWidgetHostViewAndroid::OnVSync(base::TimeTicks frame_time,
                                           base::TimeDelta vsync_period) {
   TRACE_EVENT0("cc,benchmark", "RenderWidgetHostViewAndroid::OnVSync");
-  if (!host_ || host_->is_hidden())
+  if (!host_)
     return;
 
   if (outstanding_vsync_requests_ & FLUSH_INPUT) {
@@ -1935,20 +1898,6 @@ void RenderWidgetHostViewAndroid::OnAnimate(base::TimeTicks begin_frame_time) {
     SetNeedsAnimate();
 }
 
-void RenderWidgetHostViewAndroid::OnActivityPaused() {
-  TRACE_EVENT0("browser", "RenderWidgetHostViewAndroid::OnActivityPaused");
-  DCHECK(is_showing_);
-  bool hide_frontbuffer = false;
-  bool stop_observing_root_window = false;
-  HideInternal(hide_frontbuffer, stop_observing_root_window);
-}
-
-void RenderWidgetHostViewAndroid::OnActivityResumed() {
-  TRACE_EVENT0("browser", "RenderWidgetHostViewAndroid::OnActivityResumed");
-  DCHECK(is_showing_);
-  ShowInternal();
-}
-
 void RenderWidgetHostViewAndroid::OnLostResources() {
   ReleaseLocksOnSurface();
   if (layer_.get())
diff --git a/content/browser/renderer_host/render_widget_host_view_android.h b/content/browser/renderer_host/render_widget_host_view_android.h
index 3aec51e34..f5eace1 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.h
+++ b/content/browser/renderer_host/render_widget_host_view_android.h
@@ -193,14 +193,11 @@ class CONTENT_EXPORT RenderWidgetHostViewAndroid
 
   // ui::WindowAndroidObserver implementation.
   void OnCompositingDidCommit() override;
-  void OnRootWindowVisibilityChanged(bool visible) override;
   void OnAttachCompositor() override;
   void OnDetachCompositor() override;
   void OnVSync(base::TimeTicks frame_time,
                base::TimeDelta vsync_period) override;
   void OnAnimate(base::TimeTicks begin_frame_time) override;
-  void OnActivityPaused() override;
-  void OnActivityResumed() override;
 
   // DelegatedFrameEvictor implementation
   void EvictDelegatedFrame() override;
@@ -290,8 +287,6 @@ class CONTENT_EXPORT RenderWidgetHostViewAndroid
       const cc::CompositorFrameMetadata& frame_metadata);
   void ComputeContentsSize(const cc::CompositorFrameMetadata& frame_metadata);
 
-  void ShowInternal();
-  void HideInternal(bool hide_frontbuffer, bool stop_observing_root_window);
   void AttachLayers();
   void RemoveLayers();
 
diff --git a/content/shell/android/shell_apk/src/org/chromium/content_shell_apk/ContentShellActivity.java b/content/shell/android/shell_apk/src/org/chromium/content_shell_apk/ContentShellActivity.java
index a5a9471..bc460bf 100644
--- a/content/shell/android/shell_apk/src/org/chromium/content_shell_apk/ContentShellActivity.java
+++ b/content/shell/android/shell_apk/src/org/chromium/content_shell_apk/ContentShellActivity.java
@@ -71,8 +71,7 @@ public class ContentShellActivity extends Activity {
 
         setContentView(R.layout.content_shell_activity);
         mShellManager = (ShellManager) findViewById(R.id.shell_container);
-        final boolean listenToActivityState = true;
-        mWindowAndroid = new ActivityWindowAndroid(this, listenToActivityState);
+        mWindowAndroid = new ActivityWindowAndroid(this);
         mWindowAndroid.restoreInstanceState(savedInstanceState);
         mShellManager.setWindow(mWindowAndroid);
         // Set up the animation placeholder to be the SurfaceView. This disables the
@@ -184,6 +183,14 @@ public class ContentShellActivity extends Activity {
     }
 
     @Override
+    protected void onStop() {
+        super.onStop();
+
+        ContentViewCore contentViewCore = getActiveContentViewCore();
+        if (contentViewCore != null) contentViewCore.onHide();
+    }
+
+    @Override
     protected void onStart() {
         super.onStart();
 
diff --git a/ui/android/java/src/org/chromium/ui/base/ActivityWindowAndroid.java b/ui/android/java/src/org/chromium/ui/base/ActivityWindowAndroid.java
index 5c20d72..b32cd9b 100644
--- a/ui/android/java/src/org/chromium/ui/base/ActivityWindowAndroid.java
+++ b/ui/android/java/src/org/chromium/ui/base/ActivityWindowAndroid.java
@@ -10,9 +10,6 @@ import android.content.ActivityNotFoundException;
 import android.content.Intent;
 import android.content.IntentSender.SendIntentException;
 
-import org.chromium.base.ActivityState;
-import org.chromium.base.ApplicationStatus;
-
 import java.lang.ref.WeakReference;
 
 /**
@@ -20,8 +17,7 @@ import java.lang.ref.WeakReference;
  * Activity Instance.
  * Only instantiate this class when you need the implemented features.
  */
-public class ActivityWindowAndroid
-        extends WindowAndroid implements ApplicationStatus.ActivityStateListener {
+public class ActivityWindowAndroid extends WindowAndroid {
     // Constants used for intent request code bounding.
     private static final int REQUEST_CODE_PREFIX = 1000;
     private static final int REQUEST_CODE_RANGE_SIZE = 100;
@@ -30,27 +26,9 @@ public class ActivityWindowAndroid
     private final WeakReference<Activity> mActivityRef;
     private int mNextRequestCode = 0;
 
-    /**
-     * Creates an Activity-specific WindowAndroid with associated intent functionality.
-     * TODO(jdduke): Remove this overload when all callsites have been updated to
-     * indicate their activity state listening preference.
-     * @param activity The activity associated with the WindowAndroid.
-     */
     public ActivityWindowAndroid(Activity activity) {
-        this(activity, true);
-    }
-
-    /**
-     * Creates an Activity-specific WindowAndroid with associated intent functionality.
-     * @param activity The activity associated with the WindowAndroid.
-     * @param listenToActivityState Whether to listen to activity state changes.
-     */
-    public ActivityWindowAndroid(Activity activity, boolean listenToActivityState) {
         super(activity.getApplicationContext());
         mActivityRef = new WeakReference<Activity>(activity);
-        if (listenToActivityState) {
-            ApplicationStatus.registerStateListenerForActivity(this, activity);
-        }
     }
 
     @Override
@@ -121,15 +99,6 @@ public class ActivityWindowAndroid
         return new WeakReference<Activity>(mActivityRef.get());
     }
 
-    @Override
-    public void onActivityStateChange(Activity activity, int newState) {
-        if (newState == ActivityState.PAUSED) {
-            onActivityPaused();
-        } else if (newState == ActivityState.RESUMED) {
-            onActivityResumed();
-        }
-    }
-
     private int generateNextRequestCode() {
         int requestCode = REQUEST_CODE_PREFIX + mNextRequestCode;
         mNextRequestCode = (mNextRequestCode + 1) % REQUEST_CODE_RANGE_SIZE;
diff --git a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
index 0bf7bd1..0870221 100644
--- a/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
+++ b/ui/android/java/src/org/chromium/ui/base/WindowAndroid.java
@@ -236,24 +236,6 @@ public class WindowAndroid {
     }
 
     /**
-     * For window instances associated with an activity, notifies any listeners
-     * that the activity has been paused.
-     */
-    protected void onActivityPaused() {
-        if (mNativeWindowAndroid == 0) return;
-        nativeOnActivityPaused(mNativeWindowAndroid);
-    }
-
-    /**
-     * For window instances associated with an activity, notifies any listeners
-     * that the activity has been paused.
-     */
-    protected void onActivityResumed() {
-        if (mNativeWindowAndroid == 0) return;
-        nativeOnActivityResumed(mNativeWindowAndroid);
-    }
-
-    /**
      * Responds to the intent result if the intent was created by the native window.
      * @param requestCode Request code of the requested intent.
      * @param resultCode Result code of the requested intent.
@@ -369,8 +351,6 @@ public class WindowAndroid {
     private native void nativeOnVSync(long nativeWindowAndroid,
                                       long vsyncTimeMicros,
                                       long vsyncPeriodMicros);
-    private native void nativeOnActivityPaused(long nativeWindowAndroid);
-    private native void nativeOnActivityResumed(long nativeWindowAndroid);
     private native void nativeDestroy(long nativeWindowAndroid);
 
 }
diff --git a/ui/android/window_android.cc b/ui/android/window_android.cc
index 9a476892..d8623a5 100644
--- a/ui/android/window_android.cc
+++ b/ui/android/window_android.cc
@@ -43,11 +43,6 @@ void WindowAndroid::OnCompositingDidCommit() {
                     OnCompositingDidCommit());
 }
 
-void WindowAndroid::OnVisibilityChanged(bool visible) {
-  FOR_EACH_OBSERVER(WindowAndroidObserver, observer_list_,
-                    OnRootWindowVisibilityChanged(visible));
-}
-
 void WindowAndroid::AddObserver(WindowAndroidObserver* observer) {
   if (!observer_list_.HasObserver(observer))
     observer_list_.AddObserver(observer);
@@ -105,14 +100,6 @@ void WindowAndroid::OnVSync(JNIEnv* env,
     compositor_->OnVSync(frame_time, vsync_period);
 }
 
-void WindowAndroid::OnActivityResumed(JNIEnv* env, jobject obj) {
-  FOR_EACH_OBSERVER(WindowAndroidObserver, observer_list_, OnActivityResumed());
-}
-
-void WindowAndroid::OnActivityPaused(JNIEnv* env, jobject obj) {
-  FOR_EACH_OBSERVER(WindowAndroidObserver, observer_list_, OnActivityPaused());
-}
-
 // ----------------------------------------------------------------------------
 // Native JNI methods
 // ----------------------------------------------------------------------------
diff --git a/ui/android/window_android.h b/ui/android/window_android.h
index 005f4d6..f464a11 100644
--- a/ui/android/window_android.h
+++ b/ui/android/window_android.h
@@ -43,7 +43,6 @@ class UI_ANDROID_EXPORT WindowAndroid {
 
   // Compositor callback relay.
   void OnCompositingDidCommit();
-  void OnVisibilityChanged(bool visible);
 
   void AttachCompositor(WindowAndroidCompositor* compositor);
   void DetachCompositor();
@@ -60,8 +59,6 @@ class UI_ANDROID_EXPORT WindowAndroid {
                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();
diff --git a/ui/android/window_android_observer.h b/ui/android/window_android_observer.h
index 4e97d2a..05db5ce 100644
--- a/ui/android/window_android_observer.h
+++ b/ui/android/window_android_observer.h
@@ -12,19 +12,12 @@ namespace ui {
 class UI_ANDROID_EXPORT WindowAndroidObserver {
  public:
   virtual void OnCompositingDidCommit() = 0;
-  virtual void OnRootWindowVisibilityChanged(bool visible) = 0;
   virtual void OnAttachCompositor() = 0;
   virtual void OnDetachCompositor() = 0;
   virtual void OnVSync(base::TimeTicks frame_time,
                        base::TimeDelta vsync_period) = 0;
   virtual void OnAnimate(base::TimeTicks frame_begin_time) {}
 
-  // Note that activity state callbacks will only be made if the WindowAndroid
-  // has been explicitly subscribed to receive them. The observer instance
-  // should account for whether or not this is the case.
-  virtual void OnActivityPaused() = 0;
-  virtual void OnActivityResumed() = 0;
-
  protected:
   virtual ~WindowAndroidObserver() {}
 };