[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 40ff13c4161da9f6bfc8fc400454297193a0fae2..40b1161024268c40bfc1b12155e0776e0da8a06a 100644
--- a/content/browser/renderer_host/render_widget_host_view_base.h
+++ b/content/browser/renderer_host/render_widget_host_view_base.h
@@ -92,10 +92,7 @@ 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 {}
@@ -430,9 +427,6 @@ class CONTENT_EXPORT RenderWidgetHostViewBase : public RenderWidgetHostView,
   // autofill...).
   blink::WebPopupType popup_type_;
 
-  // The background color of the web content.
-  SkColor background_color_;
-
   // 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