Allocate a FrameSinkId for RenderWidgetHostViewAura in mus+ash

content/browser/renderer_host/render_widget_host_view_aura.h

Index: content/browser/renderer_host/render_widget_host_view_aura.h
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.h b/content/browser/renderer_host/render_widget_host_view_aura.h
index c0e1fd77cd5016b2c8292ae3d5587f45d046afab..489ebc43422d6b0766dd5d33e22ec172edaa4c76 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.h
+++ b/content/browser/renderer_host/render_widget_host_view_aura.h
@@ -590,6 +590,8 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
   // provides an implementation, and directs events to |host_|.
   std::unique_ptr<RenderWidgetHostViewEventHandler> event_handler_;
 
+  cc::FrameSinkId frame_sink_id_;
+
   base::WeakPtrFactory<RenderWidgetHostViewAura> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewAura);