[Extensions] Add perf metrics for StartRequest()/HandleResponse()

extensions/renderer/request_sender.h

 // Copyright 2014 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 EXTENSIONS_RENDERER_REQUEST_SENDER_H_
 #define EXTENSIONS_RENDERER_REQUEST_SENDER_H_
 
 #include <map>
 #include <string>
 
@@ skipping 57 matching lines @@
   // In order to avoid collision, all |request_id|s passed into StartRequest()
   // should be generated by this method.
   int GetNextRequestId() const;
 
   // Makes a call to the API function |name| that is to be handled by the
   // extension host. The response to this request will be received in
   // HandleResponse().
   // TODO(koz): Remove |request_id| and generate that internally.
   //            There are multiple of these per render view though, so we'll
   //            need to vend the IDs centrally.
-  void StartRequest(Source* source,
+  // Returns true if the request is successfully sent.
+  bool StartRequest(Source* source,
                     const std::string& name,
                     int request_id,
                     bool has_callback,
                     bool for_io_thread,
                     base::ListValue* value_args);
 
   // Sends the IPC to extension host for the API function that is described
   // in |params|.
   virtual void SendRequest(content::RenderFrame* render_frame,
                            bool for_io_thread,
@@ skipping 19 matching lines @@
   PendingRequestMap pending_requests_;
 
   int source_tab_id_;  // Id of the tab sending the request, or -1 if no tab.
 
   DISALLOW_COPY_AND_ASSIGN(RequestSender);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_REQUEST_SENDER_H_