Give the main frame a RenderWidget.

chrome/browser/ui/browser.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 CHROME_BROWSER_UI_BROWSER_H_
 #define CHROME_BROWSER_UI_BROWSER_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 566 matching lines @@
                          bool* proceed_to_fire_unload) override;
   bool ShouldFocusLocationBarByDefault(content::WebContents* source) override;
   void ViewSourceForTab(content::WebContents* source,
                         const GURL& page_url) override;
   void ViewSourceForFrame(content::WebContents* source,
                           const GURL& frame_url,
                           const content::PageState& frame_page_state) override;
   void ShowRepostFormWarningDialog(content::WebContents* source) override;
   bool ShouldCreateWebContents(
       content::WebContents* web_contents,
-      int route_id,
-      int main_frame_route_id,
+      int32_t route_id,
+      int32_t main_frame_route_id,
+      int32_t main_frame_widget_route_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;
   void WebContentsCreated(content::WebContents* source_contents,
                           int opener_render_frame_id,
                           const std::string& frame_name,
                           const GURL& target_url,
                           content::WebContents* new_contents) override;
@@ skipping 226 matching lines @@
 
   bool ShouldHideUIForFullscreen() const;
 
   // Returns true if we can start the shutdown sequence for the browser, i.e.
   // the last browser window is being closed.
   bool ShouldStartShutdown() const;
 
   // Creates a BackgroundContents if appropriate; return true if one was
   // created.
   bool MaybeCreateBackgroundContents(
-      int route_id,
-      int main_frame_route_id,
+      int32_t route_id,
+      int32_t main_frame_route_id,
+      int32_t main_frame_widget_route_id,
       content::WebContents* opener_web_contents,
       const std::string& frame_name,
       const GURL& target_url,
       const std::string& partition_id,
       content::SessionStorageNamespace* session_storage_namespace);
 
   // Data members /////////////////////////////////////////////////////////////
 
   std::vector<InterstitialObserver*> interstitial_observers_;
 
@@ skipping 137 matching lines @@
   // The following factory is used for chrome update coalescing.
   base::WeakPtrFactory<Browser> chrome_updater_factory_;
 
   // The following factory is used to close the frame at a later time.
   base::WeakPtrFactory<Browser> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Browser);
 };
 
 #endif  // CHROME_BROWSER_UI_BROWSER_H_