Cleanup: Remove unneeded browser_thread.h includes.

chrome/browser/sync_file_system/drive_backend/fake_drive_service_helper.cc

 // Copyright 2014 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/sync_file_system/drive_backend/fake_drive_service_helper.h"
 
 #include "base/bind.h"
 #include "base/file_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "chrome/browser/sync_file_system/sync_file_system_test_util.h"
 #include "chrome/browser/sync_file_system/sync_status_code.h"
-#include "content/public/test/test_browser_thread.h"
 #include "google_apis/drive/drive_api_parser.h"
 #include "google_apis/drive/gdata_wapi_parser.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "webkit/browser/fileapi/file_system_url.h"
 
 #define FPL(path) FILE_PATH_LITERAL(path)
 
 using google_apis::AboutResource;
 using google_apis::GDataErrorCode;
 using google_apis::ResourceEntry;
@@ skipping 319 matching lines @@
     const std::string& content) {
   base::FilePath temp_file;
   EXPECT_TRUE(base::CreateTemporaryFileInDir(temp_dir_, &temp_file));
   EXPECT_EQ(static_cast<int>(content.size()),
             file_util::WriteFile(temp_file, content.data(), content.size()));
   return temp_file;
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system