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

components/web_contents_delegate_android/web_contents_delegate_android.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 COMPONENTS_WEB_CONTENTS_DELEGATE_ANDROID_WEB_CONTENTS_DELEGATE_ANDROID_H_
 #define COMPONENTS_WEB_CONTENTS_DELEGATE_ANDROID_WEB_CONTENTS_DELEGATE_ANDROID_H_
 
 #include "base/android/jni_weak_ref.h"
 #include "base/android/scoped_java_ref.h"
 #include "base/compiler_specific.h"
@@ skipping 62 matching lines @@
   virtual void RendererResponsive(content::WebContents* source) override;
   virtual void DidNavigateToPendingEntry(content::WebContents* source) override;
   virtual void WebContentsCreated(content::WebContents* source_contents,
                                   int opener_render_frame_id,
                                   const base::string16& frame_name,
                                   const GURL& target_url,
                                   content::WebContents* new_contents) override;
   virtual bool ShouldCreateWebContents(
       content::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,
       content::SessionStorageNamespace* session_storage_namespace) override;
   virtual bool OnGoToEntryOffset(int offset) override;
   virtual void CloseContents(content::WebContents* source) override;
   virtual void MoveContents(content::WebContents* source,
                             const gfx::Rect& pos) override;
   virtual bool AddMessageToConsole(content::WebContents* source,
@@ skipping 33 matching lines @@
   JavaObjectWeakGlobalRef weak_java_delegate_;
 
   scoped_ptr<ValidationMessageBubbleAndroid> validation_message_bubble_;
 };
 
 bool RegisterWebContentsDelegateAndroid(JNIEnv* env);
 
 }  // namespace web_contents_delegate_android
 
 #endif  // COMPONENTS_WEB_CONTENTS_DELEGATE_ANDROID_WEB_CONTENTS_DELEGATE_ANDROID_H_