Give the main frame a RenderWidget.

content/browser/frame_host/render_frame_host_impl.h

Index: content/browser/frame_host/render_frame_host_impl.h
diff --git a/content/browser/frame_host/render_frame_host_impl.h b/content/browser/frame_host/render_frame_host_impl.h
index 498785d2f8f634470b29ffee8f52eed578c04e52..f253d989145d462d844979a826e21374b9e5d97e 100644
--- a/content/browser/frame_host/render_frame_host_impl.h
+++ b/content/browser/frame_host/render_frame_host_impl.h
@@ -226,6 +226,13 @@ class CONTENT_EXPORT RenderFrameHostImpl
   // pointer to the RenderViewHost (which inherits RenderWidgetHost).
   RenderWidgetHostImpl* GetRenderWidgetHost();
 
+  // Similar to the above, but if the RenderFrameHost is the main frame, it
+  // returns the RenderWidgetHost owned by the main RenderFrameHost rather than
+  // the RenderViewHost.
+  RenderWidgetHostImpl* GetRenderWidgetHostForFrame() {
+    return render_widget_host_;
+  }
+
   // This returns the RenderWidgetHostView that can be used to control
   // focus and visibility for this frame.
   RenderWidgetHostView* GetView();