Use FrameTreeNode ID as frameId in extension APIs

content/public/browser/render_frame_host.h

 // Copyright 2013 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_RENDER_FRAME_HOST_H_
 #define CONTENT_PUBLIC_BROWSER_RENDER_FRAME_HOST_H_
 
 #include <string>
 
 #include "base/callback_forward.h"
@@ skipping 19 matching lines @@
 class SiteInstance;
 
 // The interface provides a communication conduit with a frame in the renderer.
 class CONTENT_EXPORT RenderFrameHost : public IPC::Listener,
                                        public IPC::Sender {
  public:
   // Returns the RenderFrameHost given its ID and the ID of its render process.
   // Returns nullptr if the IDs do not correspond to a live RenderFrameHost.
   static RenderFrameHost* FromID(int render_process_id, int render_frame_id);
 
+  // Returns the current RenderFrameHost associated with the frame identified by
+  // the given FrameTreeNode ID, in any WebContents. The frame may change its
+  // current RenderFrameHost over time, so the returned RenderFrameHost can be
+  // different from the RenderFrameHost that returned the ID via
+  // GetFrameTreeNodeId(). See GetFrameTreeNodeId for more details.
+  // Use WebContents::FindFrameByFrameTreeNodeId to find a RenderFrameHost in
+  // a specific WebContents.
+  // Returns nullptr if the frame does not exist.
+  static RenderFrameHost* FromFrameTreeNodeId(int frame_tree_node_id);

[avallee, 2016/04/11 18:13:19]

No implementation nor calls...

[Charlie Reis, 2016/04/11 20:41:27]

Thanks for noticing, avallee@.  Can you send a CL to remove it?  I'm happy to
approve.

+
 #if defined(OS_ANDROID)
   // Globally allows for injecting JavaScript into the main world. This feature
   // is present only to support Android WebView and must not be used in other
   // configurations.
   static void AllowInjectingJavaScriptForAndroidWebView();
 #endif
 
   // Returns a RenderFrameHost given its accessibility tree ID.
   static RenderFrameHost* FromAXTreeID(int ax_tree_id);
 
@@ skipping 11 matching lines @@
   virtual SiteInstance* GetSiteInstance() = 0;
 
   // Returns the process for this frame.
   virtual RenderProcessHost* GetProcess() = 0;
 
   // Returns the current RenderFrameHost of the parent frame, or nullptr if
   // there is no parent. The result may be in a different process than the
   // current RenderFrameHost.
   virtual RenderFrameHost* GetParent() = 0;
 
+  // Returns the FrameTreeNode ID for this frame. This ID is browser-global and
+  // uniquely identifies a frame that hosts content. The identifier is fixed at
+  // the creation of the frame and stays constant for the lifetime of the frame.
+  // When the frame is removed, the ID is not used again.
+  //
+  // A RenderFrameHost is tied to a process. Due to cross-process navigations,
+  // the RenderFrameHost may have a shorter lifetime than a frame. Consequently,
+  // the same FrameTreeNode ID may refer to a different RenderFrameHost after a
+  // navigation.
+  virtual int GetFrameTreeNodeId() = 0;
+
   // Returns the assigned name of the frame, the name of the iframe tag
   // declaring it. For example, <iframe name="framename">[...]</iframe>. It is
   // quite possible for a frame to have no name, in which case GetFrameName will
   // return an empty string.
   virtual const std::string& GetFrameName() = 0;
 
   // Returns true if the frame is out of process.
   virtual bool IsCrossProcessSubframe() = 0;
 
   // Returns the last committed URL of the frame.
@@ skipping 88 matching lines @@
 
  private:
   // This interface should only be implemented inside content.
   friend class RenderFrameHostImpl;
   RenderFrameHost() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_RENDER_FRAME_HOST_H_