Move ReadFileToString to the base namespace.

chrome/browser/sync_file_system/drive_backend/drive_file_sync_service_fake_unittest.cc

 // Copyright 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/sync_file_system/drive_backend/drive_file_sync_service.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/file_util.h"
@@ skipping 795 matching lines @@
   status = SYNC_STATUS_FAILED;
   webkit_blob::ScopedFile downloaded;
   sync_service_->DownloadRemoteVersion(
       url, versions[0].id,
       base::Bind(&DidDownloadRemoteVersion, &status, &downloaded));
   base::RunLoop().RunUntilIdle();
 
   ASSERT_EQ(SYNC_STATUS_OK, status);
 
   std::string downloaded_content;
-  EXPECT_TRUE(file_util::ReadFileToString(downloaded.path(),
-                                          &downloaded_content));
+  EXPECT_TRUE(base::ReadFileToString(downloaded.path(), &downloaded_content));
   EXPECT_EQ(content, downloaded_content);
 }
 
 TEST_F(DriveFileSyncServiceFakeTest, RegisterNewOrigin) {
   ASSERT_FALSE(IsDriveAPIDisabled());
   TestRegisterNewOrigin();
 }
 
 TEST_F(DriveFileSyncServiceFakeTest, RegisterNewOrigin_WAPI) {
   ScopedDisableDriveAPI disable_drive_api;
@@ skipping 106 matching lines @@
 }
 
 TEST_F(DriveFileSyncServiceFakeTest, GetRemoteVersions_WAPI) {
   ScopedDisableDriveAPI disable_drive_api;
   TestGetRemoteVersions();
 }
 
 #endif  // !defined(OS_ANDROID)
 
 }  // namespace sync_file_system