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..41b1fe15a5b0a943855bd69e84906db1de9402d5 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;
@@ -234,8 +230,8 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
     return touch_event_handler_region_;
   }
 
-  void set_layer_scroll_client(WebKit::WebLayerScrollClient* client) {
-    layer_scroll_client_ = client;
+  void set_did_scroll_callback(const base::Closure& callback) {
+    did_scroll_callback_ = callback;
   }
 
   void SetDrawCheckerboardForMissingTiles(bool checkerboard);
@@ -488,7 +484,7 @@ class CC_EXPORT Layer : public base::RefCounted<Layer>,
 
   ScopedPtrVector<CopyOutputRequest> copy_requests_;
 
-  WebKit::WebLayerScrollClient* layer_scroll_client_;
+  base::Closure did_scroll_callback_;
 
   DrawProperties<Layer, RenderSurface> draw_properties_;