Resend unconsumed scroll update from guest back to embedder (WebView Scroll Bubble).

content/browser/renderer_host/render_widget_host_impl.h

Index: content/browser/renderer_host/render_widget_host_impl.h
diff --git a/content/browser/renderer_host/render_widget_host_impl.h b/content/browser/renderer_host/render_widget_host_impl.h
index 56ef44edfc80fe2b97256b5e65869543e0c92356..5c179d650d0748e55da48b335e9aa66f5c234785 100644
--- a/content/browser/renderer_host/render_widget_host_impl.h
+++ b/content/browser/renderer_host/render_widget_host_impl.h
@@ -459,6 +459,8 @@ class CONTENT_EXPORT RenderWidgetHostImpl
     renderer_initialized_ = renderer_initialized;
   }
 
+  bool is_in_gesture_scroll() { return is_in_gesture_scroll_; }

[kenrb, 2015/09/14 15:48:51]

Is there a way to avoid exposing this and keeping the logic entirely in
RenderWidgetHostImpl? It would be cleaner if that was possible, in particular
because then BrowserPluginGuest could call Process*Event() methods on
RenderWidgetHostView instead of Forward*Event() methods on RenderWidgetHostImpl
(which isn't possible now because ProcessGestureEvent doesn't exist yet, but I'm
thinking forward a bit).

[wjmaclean, 2015/09/14 20:47:21]

Yes, but it involves detecting |resendSource| (now renamed |resendingPluginId|)
in the Forward*Event()s, and if necessary creating the synthetic
GestureScrollBegin/End within RenderWidgetHostImpl.

My original idea had been to keep as much of the machinery as possible in
BrowserPluginGuest to make it easier removing this later on (once OOPIF
scrolling works, this code will be unnecessary).

If you're OK with moving the extra baggage into RWHI then I'll go ahead and do
that.

+
  protected:
   RenderWidgetHostImpl* AsRenderWidgetHostImpl() override;
 
@@ -781,6 +783,8 @@ class CONTENT_EXPORT RenderWidgetHostImpl
   // not sent to the renderer.
   bool has_touch_handler_;
 
+  bool is_in_gesture_scroll_;
+
   scoped_ptr<SyntheticGestureController> synthetic_gesture_controller_;
 
   scoped_ptr<TouchEmulator> touch_emulator_;