[Extensions][TaskScheduler] Update ActivityLog for scheduling migration

chrome/browser/extensions/activity_log/activity_log.cc

 // Copyright (c) 2011 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/activity_log/activity_log.h"
 
 #include <stddef.h>
 #include <set>
 #include <utility>
 #include <vector>
@@ skipping 562 matching lines @@
       switches::kEnableExtensionActivityLogTesting);
 
   // Check if the watchdog extension is previously installed and active.
   cached_consumer_count_ =
       profile_->GetPrefs()->GetInteger(prefs::kWatchdogExtensionActive);
 
   observers_ = new base::ObserverListThreadSafe<Observer>;
 
   // Check that the right threads exist for logging to the database.
   // If not, we shouldn't try to do things that require them.
+  // TODO(devlin): We can clean this up now that we use sequenced task runners.
   if (!BrowserThread::IsMessageLoopValid(BrowserThread::DB) ||
       !BrowserThread::IsMessageLoopValid(BrowserThread::FILE) ||
       !BrowserThread::IsMessageLoopValid(BrowserThread::IO)) {
     has_threads_ = false;
   }
 
   extension_registry_observer_.Add(ExtensionRegistry::Get(profile_));
   CheckActive(true);  // use cached
   extension_system_->ready().Post(
       FROM_HERE,
@@ skipping 346 matching lines @@
   }
 }
 
 template <>
 void BrowserContextKeyedAPIFactory<ActivityLog>::DeclareFactoryDependencies() {
   DependsOn(ExtensionsBrowserClient::Get()->GetExtensionSystemFactory());
   DependsOn(ExtensionRegistryFactory::GetInstance());
 }
 
 }  // namespace extensions