Add ZoomLevelChanged and DidChangeScrollOffset to RenderViewObserver

content/renderer/render_widget.h

Index: content/renderer/render_widget.h
diff --git a/content/renderer/render_widget.h b/content/renderer/render_widget.h
index c6257bb0fae8add8beb6d07f8599d9316482a79b..becc4e31a9a5d4d30d7fdfef018a827694b4e76b 100644
--- a/content/renderer/render_widget.h
+++ b/content/renderer/render_widget.h
@@ -40,6 +40,7 @@ class SyncMessage;
 
 namespace WebKit {
 class WebMouseEvent;
+class WebMouseWheelEvent;
 class WebTouchEvent;
 class WebWidget;
 }
@@ -356,6 +357,10 @@ class CONTENT_EXPORT RenderWidget
   // just handled.
   virtual void DidHandleTouchEvent(const WebKit::WebTouchEvent& event) {}
 
+  // Called by OnHandleInputEvent() to notify subclasses that a wheel event was
+  // just handled.
+  virtual void DidHandleWheelEvent(const WebKit::WebMouseWheelEvent& event) {}
+
   // Should return true if the underlying WebWidget is responsible for
   // the scheduling of compositing requests.
   virtual bool WebWidgetHandlesCompositorScheduling() const;