Add a new resizer corner overlay.

chrome/browser/renderer_host/render_widget_host.h

Index: chrome/browser/renderer_host/render_widget_host.h
===================================================================
--- chrome/browser/renderer_host/render_widget_host.h	(revision 9328)
+++ chrome/browser/renderer_host/render_widget_host.h	(working copy)
@@ -205,6 +205,10 @@
   void ForwardKeyboardEvent(const WebKeyboardEvent& key_event);
   void ForwardInputEvent(const WebInputEvent& input_event, int event_size);
 
+  // This is for derived classes to give us access to the resizer rect.
+  // And to also expose it to the RenderWidgetHostView.
+  virtual gfx::Rect GetRootWindowResizerRect() const;
+
  protected:
   // Called when we receive a notification indicating that the renderer
   // process has gone. This will reset our state so that our state will be