Pipe the devTools FrameId from blink into the browser for headless

headless/public/headless_web_contents.h

 // Copyright 2015 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 HEADLESS_PUBLIC_HEADLESS_WEB_CONTENTS_H_
 #define HEADLESS_PUBLIC_HEADLESS_WEB_CONTENTS_H_
 
 #include <list>
 #include <string>
 #include <utility>
@@ skipping 65 matching lines @@
   // won't return a valid value until Observer::DevToolsTargetReady has been
   // signaled.
   virtual HeadlessDevToolsTarget* GetDevToolsTarget() = 0;
 
   // Close this page. |HeadlessWebContents| object will be destroyed.
   virtual void Close() = 0;
 
   // Returns the headless tab socket for JS -> C++ if one was created.
   virtual HeadlessTabSocket* GetHeadlessTabSocket() const = 0;
 
-  // Returns the frame tree node id associated with the |devtools_agent_host_id|
+  // Returns the FrameTreeNode Id associated with the |devtools_agent_host_id|
   // if any.
+  // TODO(alexclarke): Remove this, it doesn't work as expected.
   virtual bool GetFrameTreeNodeIdForDevToolsAgentHostId(
       const std::string& devtools_agent_host_id,
       int* frame_tree_node_id) const = 0;
 
  private:
   friend class HeadlessWebContentsImpl;
   HeadlessWebContents() {}
 
   DISALLOW_COPY_AND_ASSIGN(HeadlessWebContents);
 };
@@ skipping 72 matching lines @@
   gfx::Size window_size_;
   std::list<MojoService> mojo_services_;
   bool create_tab_socket_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(Builder);
 };
 
 }  // namespace headless
 
 #endif  // HEADLESS_PUBLIC_HEADLESS_WEB_CONTENTS_H_