Remove dependency on BrowserThread::FILE from Sync code

chrome/browser/sync/glue/extension_setting_data_type_controller.cc

Index: chrome/browser/sync/glue/extension_setting_data_type_controller.cc
diff --git a/chrome/browser/sync/glue/extension_setting_data_type_controller.cc b/chrome/browser/sync/glue/extension_setting_data_type_controller.cc
index f8856077bcd24d64e1b5b59c291fc4b1d8481571..d7343a8eba2554e725fb6bd5b74dc716ee3f8194 100644
--- a/chrome/browser/sync/glue/extension_setting_data_type_controller.cc
+++ b/chrome/browser/sync/glue/extension_setting_data_type_controller.cc
@@ -6,15 +6,13 @@
 
 #include "base/bind.h"
 #include "base/metrics/histogram_macros.h"
+#include "chrome/browser/extensions/api/storage/backend_task_runner.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "components/sync/driver/generic_change_processor.h"
 #include "components/sync/model/syncable_service.h"
-#include "content/public/browser/browser_thread.h"
 #include "extensions/browser/extension_system.h"
 
-using content::BrowserThread;
-
 namespace browser_sync {
 
 ExtensionSettingDataTypeController::ExtensionSettingDataTypeController(
@@ -22,12 +20,11 @@ ExtensionSettingDataTypeController::ExtensionSettingDataTypeController(
     const base::Closure& dump_stack,
     syncer::SyncClient* sync_client,
     Profile* profile)
-    : AsyncDirectoryTypeController(
-          type,
-          dump_stack,
-          sync_client,
-          syncer::GROUP_FILE,
-          BrowserThread::GetTaskRunnerForThread(BrowserThread::FILE)),
+    : AsyncDirectoryTypeController(type,
+                                   dump_stack,
+                                   sync_client,
+                                   syncer::GROUP_FILE,
+                                   extensions::GetBackendTaskRunner()),
       profile_(profile) {
   DCHECK(type == syncer::EXTENSION_SETTINGS || type == syncer::APP_SETTINGS);
 }