[content] Fix background color update handling in RWHVAura.

content/public/browser/render_widget_host_view.h

Index: content/public/browser/render_widget_host_view.h
diff --git a/content/public/browser/render_widget_host_view.h b/content/public/browser/render_widget_host_view.h
index 71c693bf7c3c09c90b6df776d1afe9dff015fbf2..6cf4da9d4590369b50e17658a6f08ddd46061c5c 100644
--- a/content/public/browser/render_widget_host_view.h
+++ b/content/public/browser/render_widget_host_view.h
@@ -128,13 +128,14 @@ class CONTENT_EXPORT RenderWidgetHostView {
   virtual base::string16 GetSelectedText() = 0;
 
   // Subclasses should override this method to set the background color. |color|
-  // could be transparent or opaque.
+  // has to be either SK_ColorTRANSPARENT or opaque. If set to
+  // SK_ColorTRANSPARENT, the renderer's background color will be overridden to
+  // be fully transparent.
   virtual void SetBackgroundColor(SkColor color) = 0;
+  virtual SkColor background_color() const = 0;

[danakj, 2017/02/28 17:52:31]

Technically this breaks (already did) the style guide as virtuals should be
BackgroundColor() styled. But there's a billion call sites probably. If you're
adventurous it might be nice to fix it in another CL real quick.

[Eric Seckler, 2017/03/01 10:22:09]

Yeah, I was considering doing that, but it seemed the effort required to find
all call sites on all platforms (afaik code search references only work on
linux?) was larger than the benefit -.-

Do we have a tool that can help with such a change, other than trial-and-error
on the different trybots?

   // Convenience method to fill the background layer with the default color by
   // calling |SetBackgroundColor|.
-  virtual SkColor background_color() = 0;
   virtual void SetBackgroundColorToDefault() = 0;
-  virtual bool GetBackgroundOpaque() = 0;
 
   // Return value indicates whether the mouse is locked successfully or not.
   virtual bool LockMouse() = 0;