cc: Create a LayerScrollClient interface and an adapter class in compositor_bindings.

cc/layers/layer.h

Index: cc/layers/layer.h
diff --git a/cc/layers/layer.h b/cc/layers/layer.h
index 51a91cb076c8fdf4033b850cb6284fd039d461b7..245623982d3447a1cf89a49a5aa9290bac954a4a 100644
--- a/cc/layers/layer.h
+++ b/cc/layers/layer.h
@@ -30,10 +30,6 @@
 #include "ui/gfx/rect_f.h"
 #include "ui/gfx/transform.h"
 
-namespace WebKit {
-class WebLayerScrollClient;
-}
-
 namespace cc {
 
 class Animation;
@@ -43,6 +39,7 @@ class CopyOutputRequest;
 class LayerAnimationDelegate;
 class LayerAnimationEventObserver;
 class LayerImpl;
+class LayerScrollClient;
 class LayerTreeHost;
 class LayerTreeImpl;
 class PriorityCalculator;
@@ -234,7 +231,7 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
     return touch_event_handler_region_;
   }
 
-  void set_layer_scroll_client(WebKit::WebLayerScrollClient* client) {
+  void set_layer_scroll_client(LayerScrollClient* client) {
     layer_scroll_client_ = client;
   }
 
@@ -488,7 +485,7 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
 
   ScopedPtrVector<CopyOutputRequest> copy_requests_;
 
-  WebKit::WebLayerScrollClient* layer_scroll_client_;
+  LayerScrollClient* layer_scroll_client_;
 
   DrawProperties<Layer, RenderSurface> draw_properties_;