[content] Fix background color update handling in RWHVAura.

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 dabb04812ca2bc06b00a9089d49b27dace889d67..08da466fc38d8066461803a183f24882be69d3c1 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.h
+++ b/content/browser/renderer_host/render_widget_host_view_aura.h
@@ -465,6 +465,10 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
   // Adds/Removes frame observer based on state.
   void UpdateNeedsBeginFramesInternal();
 
+  // Applies background color without notifying the RenderWidget about
+  // opaqueness changes.
+  void UpdateBackgroundColorFromRenderer(SkColor color);
+
   // The model object.
   RenderWidgetHostImpl* const host_;
 
@@ -586,6 +590,9 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
   // provides an implementation, and directs events to |host_|.
   std::unique_ptr<RenderWidgetHostViewEventHandler> event_handler_;
 
+  // Body background color of the underlying document.
+  SkColor cached_background_color_;
+
   base::WeakPtrFactory<RenderWidgetHostViewAura> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewAura);