Use FrameTreeNode ID as frameId in extension APIs

content/browser/web_contents/web_contents_impl.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_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 216 matching lines @@
   void SetDelegate(WebContentsDelegate* delegate) override;
   NavigationControllerImpl& GetController() override;
   const NavigationControllerImpl& GetController() const override;
   BrowserContext* GetBrowserContext() const override;
   const GURL& GetURL() const override;
   const GURL& GetVisibleURL() const override;
   const GURL& GetLastCommittedURL() const override;
   RenderProcessHost* GetRenderProcessHost() const override;
   RenderFrameHostImpl* GetMainFrame() override;
   RenderFrameHostImpl* GetFocusedFrame() override;
+  RenderFrameHostImpl* FindByFrameTreeNodeID(int frame_tree_node_id) override;
   void ForEachFrame(
       const base::Callback<void(RenderFrameHost*)>& on_frame) override;
   void SendToAllFrames(IPC::Message* message) override;
   RenderViewHostImpl* GetRenderViewHost() const override;
   int GetRoutingID() const override;
   RenderWidgetHostView* GetRenderWidgetHostView() const override;
   void ClosePage() override;
   RenderWidgetHostView* GetFullscreenRenderWidgetHostView() const override;
   SkColor GetThemeColor() const override;
   WebUI* CreateSubframeWebUI(const GURL& url,
@@ skipping 1081 matching lines @@
   // Adds/removes a callback called on creation of each new WebContents.
   static void AddCreatedCallbackForTesting(const CreatedCallback& callback);
   static void RemoveCreatedCallbackForTesting(const CreatedCallback& callback);
 
   DISALLOW_COPY_AND_ASSIGN(FriendZone);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_