Set up the infrastructure for Extension event metrics.

chrome/browser/extensions/api/file_system/file_system_api.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/file_system/file_system_api.h"
 
 #include <set>
 #include <vector>
 
 #include "apps/saved_files_service.h"
@@ skipping 312 matching lines @@
   ConsentProviderDelegate consent_provider_delegate(profile, nullptr);
   ConsentProvider consent_provider(&consent_provider_delegate);
   extensions::api::file_system::VolumeListChangedEvent event_args;
   FillVolumeList(profile, &event_args.volumes);
   for (const auto& extension : registry->enabled_extensions()) {
     if (!consent_provider.IsGrantable(*extension.get()))
       continue;
     event_router->DispatchEventToExtension(
         extension->id(),
         make_scoped_ptr(new Event(
+            events::UNKNOWN,
             extensions::api::file_system::OnVolumeListChanged::kEventName,
             extensions::api::file_system::OnVolumeListChanged::Create(
                 event_args))));
   }
 }
 
 ConsentProvider::ConsentProvider(DelegateInterface* delegate)
     : delegate_(delegate) {
   DCHECK(delegate_);
 }
@@ skipping 1105 matching lines @@
   std::vector<linked_ptr<Volume>> result_volume_list;
   FillVolumeList(chrome_details_.GetProfile(), &result_volume_list);
 
   return RespondNow(
       ArgumentList(extensions::api::file_system::GetVolumeList::Results::Create(
                        result_volume_list).Pass()));
 }
 #endif
 
 }  // namespace extensions