Allows observers to be notified when layer animations complete.

ui/gfx/compositor/layer_animation_observer.h

+// Copyright (c) 2011 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_GFX_COMPOSITOR_LAYER_ANIMATION_OBSERVER_H_
+#define UI_GFX_COMPOSITOR_LAYER_ANIMATION_OBSERVER_H_
+#pragma once
+
+#include "ui/gfx/compositor/compositor_export.h"
+
+namespace ui {
+
+class LayerAnimationSequence;
+
+// LayerAnimationObservers are notified when animations complete.
+class COMPOSITOR_EXPORT LayerAnimationObserver  {
+ public:
+  // Called when the |sequence| ends. Not called if |sequence| is aborted.
+  virtual void OnLayerAnimationEnded(
+      const LayerAnimationSequence* sequence) = 0;

[sky, 2011/10/28 22:11:38]

Most folks are only going to care about ended. Because of this I tend to think
all of these should be non-pure methods.

+
+  // Called if |sequence| is aborted for any reason.
+  virtual void OnLayerAnimationAborted(
+      const LayerAnimationSequence* sequence) = 0;
+
+  // Called when the animation is scheduled.
+  virtual void OnLayerAnimationScheduled(
+      const LayerAnimationSequence* sequence) = 0;
+
+ protected:
+  virtual ~LayerAnimationObserver() {}
+};
+
+}  // namespace ui
+
+#endif  // UI_GFX_COMPOSITOR_LAYER_ANIMATION_OBSERVER_H_