Add the main frame routing ID to WebContentsDelegate, use it in BackgroundContents.

content/public/browser/web_contents_delegate.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 CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_DELEGATE_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_DELEGATE_H_
 
 #include <set>
 #include <string>
 
@@ skipping 291 matching lines @@
   virtual bool OnGoToEntryOffset(int offset);
 
   // Allows delegate to control whether a WebContents will be created. Returns
   // true to allow the creation. Default is to allow it. In cases where the
   // delegate handles the creation/navigation itself, it will use |target_url|.
   // The embedder has to synchronously adopt |route_id| or else the view will
   // be destroyed.
   virtual bool ShouldCreateWebContents(
       WebContents* web_contents,
       int route_id,
+      int main_frame_route_id,
       WindowContainerType window_container_type,
       const base::string16& frame_name,
       const GURL& target_url,
       const std::string& partition_id,
       SessionStorageNamespace* session_storage_namespace);
 
   // Notifies the delegate about the creation of a new WebContents. This
   // typically happens when popups are created.
   virtual void WebContentsCreated(WebContents* source_contents,
                                   int opener_render_frame_id,
@@ skipping 182 matching lines @@
   // Called when |this| is no longer the WebContentsDelegate for |source|.
   void Detach(WebContents* source);
 
   // The WebContents that this is currently a delegate for.
   std::set<WebContents*> attached_contents_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_DELEGATE_H_