Added UMA stats for extensions events on addListener.

chrome/browser/extensions/event_router.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 CHROME_BROWSER_EXTENSIONS_EVENT_ROUTER_H_
 #define CHROME_BROWSER_EXTENSIONS_EVENT_ROUTER_H_
 
 #include <map>
 #include <set>
 #include <string>
 #include <utility>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/hash_tables.h"
 #include "base/memory/linked_ptr.h"
 #include "base/memory/ref_counted.h"
 #include "base/values.h"
 #include "chrome/browser/extensions/event_listener_map.h"
+#include "chrome/browser/extensions/extension_event_histogram_value.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "extensions/common/event_filtering_info.h"
 #include "ipc/ipc_sender.h"
 
 class GURL;
 class Profile;
 
 namespace content {
 class BrowserContext;
@@ skipping 186 matching lines @@
       const linked_ptr<Event>& event);
 
   // Track of the number of dispatched events that have not yet sent an
   // ACK from the renderer.
   void IncrementInFlightEvents(Profile* profile,
                                const Extension* extension);
 
   void DispatchPendingEvent(const linked_ptr<Event>& event,
                             ExtensionHost* host);
 
+  void RecordEventListenerAdded(const std::string& event_name);
+
   // Implementation of EventListenerMap::Delegate.
   virtual void OnListenerAdded(const EventListener* listener) OVERRIDE;
   virtual void OnListenerRemoved(const EventListener* listener) OVERRIDE;
 
   Profile* profile_;
 
   content::NotificationRegistrar registrar_;
 
   EventListenerMap listeners_;
 
+  std::map<std::string, extensions::events::HistogramValue> histogram_values_;
+
   typedef base::hash_map<std::string, Observer*> ObserverMap;
   ObserverMap observers_;
 
   ActivityLog* activity_log_;
 
   // True if we should dispatch the event signalling that Chrome was updated
   // upon loading an extension.
   bool dispatch_chrome_updated_event_;
 
   DISALLOW_COPY_AND_ASSIGN(EventRouter);
@@ skipping 56 matching lines @@
   EventListenerInfo(const std::string& event_name,
                     const std::string& extension_id);
 
   const std::string event_name;
   const std::string extension_id;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EVENT_ROUTER_H_