Use ThreadChecker rather than DCHECK_CURRENTLY_ON.

chrome/browser/extensions/extension_service.cc

 // Copyright (c) 2013 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/extension_service.h"
 
 #include <algorithm>
 #include <iterator>
 #include <set>
 
@@ skipping 1878 matching lines @@
     extension_sync_service_->SyncExtensionChangeIfNeeded(*extension);
 }
 
 const Extension* ExtensionService::GetPendingExtensionUpdate(
     const std::string& id) const {
   return delayed_installs_.GetByID(id);
 }
 
 void ExtensionService::RegisterContentSettings(
     HostContentSettingsMap* host_content_settings_map) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
   host_content_settings_map->RegisterProvider(
       HostContentSettingsMap::INTERNAL_EXTENSION_PROVIDER,
       scoped_ptr<content_settings::ObservableProvider>(
           new content_settings::InternalExtensionProvider(this)));
 
   host_content_settings_map->RegisterProvider(
       HostContentSettingsMap::CUSTOM_EXTENSION_PROVIDER,
       scoped_ptr<content_settings::ObservableProvider>(
           new content_settings::CustomExtensionProvider(
               extensions::ContentSettingsService::Get(
@@ skipping 460 matching lines @@
 }
 
 void ExtensionService::OnProfileDestructionStarted() {
   ExtensionIdSet ids_to_unload = registry_->enabled_extensions().GetIDs();
   for (ExtensionIdSet::iterator it = ids_to_unload.begin();
        it != ids_to_unload.end();
        ++it) {
     UnloadExtension(*it, UnloadedExtensionInfo::REASON_PROFILE_SHUTDOWN);
   }
 }