Set up the infrastructure for Extension event metrics.

chrome/browser/extensions/api/settings_private/settings_private_event_router.cc

 // 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.
 
 #include "chrome/browser/extensions/api/settings_private/settings_private_event_router.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 121 matching lines @@
   api::settings_private::PrefObject* pref_object =
       prefs_util_->GetPref(pref_name).release();
 
   std::vector<linked_ptr<api::settings_private::PrefObject>> prefs;
   prefs.push_back(linked_ptr<api::settings_private::PrefObject>(pref_object));
 
   scoped_ptr<base::ListValue> args(
       api::settings_private::OnPrefsChanged::Create(prefs));
 
   scoped_ptr<Event> extension_event(new Event(
-      api::settings_private::OnPrefsChanged::kEventName, args.Pass()));
+      events::UNKNOWN, api::settings_private::OnPrefsChanged::kEventName,
+      args.Pass()));
   event_router->BroadcastEvent(extension_event.Pass());
 }
 
 SettingsPrivateEventRouter* SettingsPrivateEventRouter::Create(
     content::BrowserContext* context) {
   return new SettingsPrivateEventRouter(context);
 }
 
 }  // namespace extensions