Enable range-based for loops to loop over a WebContents' frame hosts.

content/public/browser/web_contents.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_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_
 
 #include <stdint.h>
 
 #include <set>
@@ skipping 210 matching lines @@
       int frame_tree_node_id) = 0;
 
   // Calls |on_frame| for each frame in the currently active view.
   // Note: The RenderFrameHost parameter is not guaranteed to have a live
   // RenderFrame counterpart in the renderer process. Callbacks should check
   // IsRenderFrameLive, as sending IPC messages to it in this case will fail
   // silently.
   virtual void ForEachFrame(
       const base::Callback<void(RenderFrameHost*)>& on_frame) = 0;
 
+  // Returns a vector of all RenderFrameHosts in the currently active view in
+  // breadth-first traversal order.
+  virtual std::vector<RenderFrameHost*> FrameHosts() = 0;
+
   // Sends the given IPC to all frames in the currently active view and returns
   // the number of sent messages (i.e. the number of processed frames). This is
   // a convenience method instead of calling ForEach.
   virtual int SendToAllFrames(IPC::Message* message) = 0;
 
   // Gets the current RenderViewHost for this tab.
   virtual RenderViewHost* GetRenderViewHost() const = 0;
 
   // Gets the current RenderViewHost's routing id. Returns
   // MSG_ROUTING_NONE when there is no RenderViewHost.
@@ skipping 469 matching lines @@
 
  private:
   // This interface should only be implemented inside content.
   friend class WebContentsImpl;
   WebContents() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_