Notify OverscrollController of gesture events in plugins.

content/browser/renderer_host/render_widget_host_view_base.h

Index: content/browser/renderer_host/render_widget_host_view_base.h
diff --git a/content/browser/renderer_host/render_widget_host_view_base.h b/content/browser/renderer_host/render_widget_host_view_base.h
index 904897ab8b702d0338c24fe88edc95dac5aef4c4..1c44a7a8ab48c2c6adf5ae2031a9bfdac0e30513 100644
--- a/content/browser/renderer_host/render_widget_host_view_base.h
+++ b/content/browser/renderer_host/render_widget_host_view_base.h
@@ -188,6 +188,10 @@ class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
   virtual InputEventAckState FilterInputEvent(
       const blink::WebInputEvent& input_event);
 
+  // Allows a root RWHV to filter gesture events in a child.
+  virtual InputEventAckState FilterChildGestureEvent(
+      const blink::WebGestureEvent& gesture_event);
+
   // Called by the host when it requires an input flush; the flush call should
   // by synchronized with BeginFrame.
   virtual void OnSetNeedsFlushInput() = 0;