Move ReadFileToString to the base namespace.

chrome/browser/extensions/gtalk_extension_browsertest.cc

 // Copyright (c) 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 "base/bind.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/extension_browsertest.h"
 #include "chrome/browser/extensions/extension_host.h"
 #include "chrome/browser/extensions/extension_process_manager.h"
@@ skipping 51 matching lines @@
       WebContents* web_contents = WebContents::FromRenderViewHost(*iter);
       std::string url = web_contents->GetURL().spec();
       if (url.find(url_query) != std::string::npos)
         matching_views.push_back(*iter);
     }
     return matching_views;
   }
 
   std::string ReadCurrentVersion() {
     std::string response;
-    EXPECT_TRUE(file_util::ReadFileToString(
+    EXPECT_TRUE(base::ReadFileToString(
       test_data_dir_.AppendASCII("gtalk").AppendASCII("current_version"),
       &response));
     return response;
   }
 
  private:
   std::string installed_extension_id_;
 };
 
 IN_PROC_BROWSER_TEST_F(GtalkExtensionTest, InstallCurrent) {
   content::WindowedNotificationObserver panel_loaded(
     chrome::NOTIFICATION_EXTENSION_VIEW_REGISTERED,
     content::NotificationService::AllSources());
   InstallGtalkExtension(ReadCurrentVersion());
   panel_loaded.Wait();
   ASSERT_TRUE(GetViewer());
 }