[content] Fix background color update handling in RWHVAura.

content/browser/renderer_host/render_widget_host_view_android.h

Index: content/browser/renderer_host/render_widget_host_view_android.h
diff --git a/content/browser/renderer_host/render_widget_host_view_android.h b/content/browser/renderer_host/render_widget_host_view_android.h
index dc3c6e7052ce25046361bde0d570bc6141b02f41..7e0d0bd56f85cd892e37e492c39d88278234ef10 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.h
+++ b/content/browser/renderer_host/render_widget_host_view_android.h
@@ -112,6 +112,7 @@ class CONTENT_EXPORT RenderWidgetHostViewAndroid
   void SetTooltipText(const base::string16& tooltip_text) override;
   bool HasAcceleratedSurface(const gfx::Size& desired_size) override;
   void SetBackgroundColor(SkColor color) override;
+  SkColor background_color() const override;
   void CopyFromCompositingSurface(
       const gfx::Rect& src_subrect,
       const gfx::Size& dst_size,
@@ -331,6 +332,9 @@ class CONTENT_EXPORT RenderWidgetHostViewAndroid
 
   ImeAdapterAndroid ime_adapter_android_;
 
+  // The background color of the widget.
+  SkColor background_color_;
+
   // Body background color of the underlying document.
   SkColor cached_background_color_;