Give the main frame a RenderWidget.

ui/views/controls/webview/web_dialog_view.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_VIEWS_CONTROLS_WEBVIEW_WEB_DIALOG_VIEW_H_
 #define UI_VIEWS_CONTROLS_WEBVIEW_WEB_DIALOG_VIEW_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 95 matching lines @@
                       const gfx::Rect& initial_rect,
                       bool user_gesture,
                       bool* was_blocked) override;
   void LoadingStateChanged(content::WebContents* source,
                            bool to_different_document) override;
   void BeforeUnloadFired(content::WebContents* tab,
                          bool proceed,
                          bool* proceed_to_fire_unload) override;
   bool ShouldCreateWebContents(
       content::WebContents* web_contents,
-      int route_id,
-      int main_frame_route_id,
+      int32 route_id,
+      int32 main_frame_route_id,
+      int32 main_frame_widget_route_id,
+      int32 surface_id,
       WindowContainerType window_container_type,
       const std::string& frame_name,
       const GURL& target_url,
       const std::string& partition_id,
       content::SessionStorageNamespace* session_storage_namespace) override;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(WebDialogBrowserTest, WebContentRendered);
 
   // Initializes the contents of the dialog.
@@ skipping 24 matching lines @@
 
   // Whether CloseContents() has been called.
   bool close_contents_called_;
 
   DISALLOW_COPY_AND_ASSIGN(WebDialogView);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_WEBVIEW_WEB_DIALOG_VIEW_H_