Add a bit to not bubble scrolls to parent scrolling layers

cc/layer_tree_host_impl.h

Index: cc/layer_tree_host_impl.h
diff --git a/cc/layer_tree_host_impl.h b/cc/layer_tree_host_impl.h
index 2e287c81e09cb2ae32651eda7afe94d0959ab9d3..f164f54bfd77f0143f7b00ef6edff0725848329a 100644
--- a/cc/layer_tree_host_impl.h
+++ b/cc/layer_tree_host_impl.h
@@ -76,7 +76,7 @@ public:
 
     // InputHandlerClient implementation
     virtual InputHandlerClient::ScrollStatus scrollBegin(gfx::Point, InputHandlerClient::ScrollInputType) OVERRIDE;
-    virtual bool scrollBy(const gfx::Point&, const gfx::Vector2d&) OVERRIDE;
+    virtual bool scrollBy(const gfx::Point&, const gfx::Vector2d&, bool shouldBubble) OVERRIDE;
     virtual void scrollEnd() OVERRIDE;
     virtual void pinchGestureBegin() OVERRIDE;
     virtual void pinchGestureUpdate(float, gfx::Point) OVERRIDE;
@@ -326,6 +326,7 @@ private:
     // by the next sync from the main thread.
     scoped_ptr<LayerTreeImpl> m_recycleTree;
 
+    bool m_didScrollOnce;
     bool m_scrollDeltaIsInViewportSpace;
     LayerTreeSettings m_settings;
     LayerTreeDebugState m_debugState;