[content] Fix background color update handling in RWHVAura.

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 b7e0cda7766034cfe42ee7698329d66fe6aefed0..88a6cbce721caf2cd8f7e756256439270c6a75c9 100644
--- a/content/browser/renderer_host/render_widget_host_view_base.h
+++ b/content/browser/renderer_host/render_widget_host_view_base.h
@@ -88,10 +88,7 @@ class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
 
   // RenderWidgetHostView implementation.
   RenderWidgetHost* GetRenderWidgetHost() const override;
-  void SetBackgroundColor(SkColor color) override;
-  SkColor background_color() override;
   void SetBackgroundColorToDefault() final;
-  bool GetBackgroundOpaque() override;
   ui::TextInputClient* GetTextInputClient() override;
   void WasUnOccluded() override {}
   void WasOccluded() override {}
@@ -446,9 +443,6 @@ class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
   // autofill...).
   blink::WebPopupType popup_type_;
 
-  // The background color of the web content.
-  SkColor background_color_;

[nasko, 2017/03/01 18:24:53]

Why remove it from the base class and have it added in each derived class?

[danakj, 2017/03/01 18:35:10]

Because the subclass needs to change the value returned by background_color()
without calling SetBackgroundColor() which would have side effects.

[danakj, 2017/03/01 18:35:35]

https://codereview.chromium.org/2702153003/#msg18
https://codereview.chromium.org/2702153003/#msg19

-
   // While the mouse is locked, the cursor is hidden from the user. Mouse events
   // are still generated. However, the position they report is the last known
   // mouse position just as mouse lock was entered; the movement they report