Animated Rotation

ui/gfx/compositor/layer.h

Index: ui/gfx/compositor/layer.h
diff --git a/ui/gfx/compositor/layer.h b/ui/gfx/compositor/layer.h
index d523c9cf6e7de57acec60f623992d1a889ed0459..7679ca2524de3177394e858d1754e20606a2b532 100644
--- a/ui/gfx/compositor/layer.h
+++ b/ui/gfx/compositor/layer.h
@@ -9,6 +9,7 @@
 #include <vector>
 
 #include "base/memory/ref_counted.h"
+#include "base/observer_list.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/transform.h"
 #include "ui/gfx/compositor/compositor.h"
@@ -18,6 +19,7 @@ class SkCanvas;
 namespace ui {
 
 class Compositor;
+class LayerObserver;
 class Texture;
 
 // Layer manages a texture, transform and a set of child Layers. Any View that
@@ -79,6 +81,11 @@ class COMPOSITOR_EXPORT Layer {
   // Resets the canvas of the texture.
   void SetCanvas(const SkCanvas& canvas, const gfx::Point& origin);
 
+  // Layers do not own observers. It is the responsibility of the observer to
+  // remove itself when it is done observing.
+  void AddObserver(LayerObserver* observer);
+  void RemoveObserver(LayerObserver* observer);
+
 // Draws the layer with hole if hole is non empty.
 // hole looks like:
 //
@@ -134,6 +141,8 @@ class COMPOSITOR_EXPORT Layer {
 
   gfx::Rect hole_rect_;
 
+  ObserverList<LayerObserver> observer_list_;
+
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };