Move ReadFileToString to the base namespace.

extensions/browser/file_reader_unittest.cc

 // Copyright (c) 2011 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 "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/file_util.h"
 #include "base/files/file_path.h"
 #include "base/message_loop/message_loop.h"
 #include "base/path_service.h"
@@ skipping 43 matching lines @@
 
 void RunBasicTest(const char* filename) {
   base::FilePath path;
   PathService::Get(DIR_TEST_DATA, &path);
   std::string extension_id = id_util::GenerateId("test");
   ExtensionResource resource(
       extension_id, path, base::FilePath().AppendASCII(filename));
   path = path.AppendASCII(filename);
 
   std::string file_contents;
-  ASSERT_TRUE(file_util::ReadFileToString(path, &file_contents));
+  ASSERT_TRUE(base::ReadFileToString(path, &file_contents));
 
   Receiver receiver;
 
   scoped_refptr<FileReader> file_reader(
       new FileReader(resource, receiver.NewCallback()));
   file_reader->Start();
 
   base::MessageLoop::current()->Run();
 
   EXPECT_TRUE(receiver.succeeded());
@@ skipping 21 matching lines @@
   scoped_refptr<FileReader> file_reader(
       new FileReader(resource, receiver.NewCallback()));
   file_reader->Start();
 
   base::MessageLoop::current()->Run();
 
   EXPECT_FALSE(receiver.succeeded());
 }
 
 }  // namespace extensions