Switch BackgroundContents to use TabContents instead of RenderViewHost.

content/browser/renderer_host/render_view_host_delegate.h

Index: content/browser/renderer_host/render_view_host_delegate.h
===================================================================
--- content/browser/renderer_host/render_view_host_delegate.h	(revision 109469)
+++ content/browser/renderer_host/render_view_host_delegate.h	(working copy)
@@ -201,11 +201,6 @@
   // jam as reviewers before you use this method. http://crbug.com/82582
   virtual TabContents* GetAsTabContents();
 
-  // Return this object cast to a BackgroundContents, if it is one. If the
-  // object is not a BackgroundContents, returns NULL.
-  // DEPRECATED: http://crbug.com/98934
-  virtual BackgroundContents* GetAsBackgroundContents();
-
   // Return type of RenderView which is attached with this object.
   virtual content::ViewType GetRenderViewType() const = 0;