Move ReadFileToString to the base namespace.

chrome/browser/chromeos/drive/fake_file_system_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/chromeos/drive/fake_file_system.h"
 
 #include "base/file_util.h"
 #include "base/run_loop.h"
 #include "chrome/browser/chromeos/drive/file_system_util.h"
 #include "chrome/browser/drive/fake_drive_service.h"
@@ skipping 76 matching lines @@
   // Cache file should be available.
   ASSERT_FALSE(cache_file_path.empty());
 
   // There should be a cache file so no data should be downloaded.
   EXPECT_TRUE(get_content_callback.data().empty());
   EXPECT_EQ(FILE_ERROR_OK, completion_error);
 
   // Make sure the cached file's content.
   std::string cache_file_content;
   ASSERT_TRUE(
-      file_util::ReadFileToString(cache_file_path, &cache_file_content));
+      base::ReadFileToString(cache_file_path, &cache_file_content));
   EXPECT_EQ(content, cache_file_content);
 }
 
 TEST_F(FakeFileSystemTest, GetFileContentByPath_Directory) {
   FileError initialize_error = FILE_ERROR_FAILED;
   scoped_ptr<ResourceEntry> entry;
   base::FilePath cache_file_path;
   google_apis::test_util::TestGetContentCallback get_content_callback;
   FileError completion_error = FILE_ERROR_FAILED;
   base::Closure cancel_download;
@@ skipping 45 matching lines @@
       util::GetDriveMyDriveRootPath().AppendASCII("Invalid File Name"),
       google_apis::test_util::CreateCopyResultCallback(&error, &entry));
   base::RunLoop().RunUntilIdle();
 
   ASSERT_EQ(FILE_ERROR_NOT_FOUND, error);
   ASSERT_FALSE(entry);
 }
 
 }  // namespace test_util
 }  // namespace drive