Set up the infrastructure for Extension event metrics.

chrome/browser/extensions/api/preference/preference_helpers.cc

 // 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.
 
 #include "chrome/browser/extensions/api/preference/preference_helpers.h"
 
 #include "base/json/json_writer.h"
 #include "base/prefs/pref_service.h"
 #include "base/values.h"
 #include "chrome/browser/extensions/api/preference/preference_api.h"
@@ skipping 108 matching lines @@
           restrict_to_profile = profile->GetOffTheRecordProfile();
         } else if (!incognito &&
                    PreferenceAPI::Get(profile)->DoesExtensionControlPref(
                        extension->id(), browser_pref, &from_incognito) &&
                    from_incognito) {
           restrict_to_profile = profile;
         }
       }
 
       scoped_ptr<base::ListValue> args_copy(args->DeepCopy());
-      scoped_ptr<Event> event(new Event(event_name, args_copy.Pass()));
+      scoped_ptr<Event> event(
+          new Event(events::UNKNOWN, event_name, args_copy.Pass()));
       event->restrict_to_browser_context = restrict_to_profile;
       router->DispatchEventToExtension(extension->id(), event.Pass());
     }
   }
 }
 
 }  // namespace preference_helpers
 }  // namespace extensions