[Extensions] Add metrics for asynchronous port creation

extensions/renderer/extension_frame_helper.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 EXTENSIONS_RENDERER_EXTENSION_FRAME_HELPER_H_
 #define EXTENSIONS_RENDERER_EXTENSION_FRAME_HELPER_H_
 
 #include <vector>
 
 #include "base/macros.h"
@@ skipping 78 matching lines @@
                      bool include_tls_channel_id,
                      const base::Callback<void(int)>& callback);
   void RequestTabPortId(const ExtensionMsg_TabTargetConnectionInfo& info,
                         const std::string& extension_id,
                         const std::string& channel_name,
                         const base::Callback<void(int)>& callback);
   void RequestNativeAppPortId(const std::string& native_app_name,
                               const base::Callback<void(int)>& callback);
 
  private:
+  struct PendingPortRequest;
+
   // RenderFrameObserver implementation.
   void DidCreateDocumentElement() override;
   void DidCreateNewDocument() override;
   void DidMatchCSS(
       const blink::WebVector<blink::WebString>& newly_matching_selectors,
       const blink::WebVector<blink::WebString>& stopped_matching_selectors)
           override;
   void DidCreateScriptContext(v8::Local<v8::Context>,
                               int extension_group,
                               int world_id) override;
@@ skipping 45 matching lines @@
   // Callbacks to be run at the next RunScriptsAtDocumentStart notification.
   std::vector<base::Closure> document_element_created_callbacks_;
 
   // Callbacks to be run at the next RunScriptsAtDocumentEnd notification.
   std::vector<base::Closure> document_load_finished_callbacks_;
 
   // Counter for port requests.
   int next_port_request_id_;
 
   // Map of port requests to callbacks.
-  std::map<int, base::Callback<void(int)>> pending_port_requests_;
+  std::map<int, std::unique_ptr<PendingPortRequest>> pending_port_requests_;
 
   base::WeakPtrFactory<ExtensionFrameHelper> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionFrameHelper);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_EXTENSION_FRAME_HELPER_H_