Convert string16 to base::string16 in content.

content/shell/browser/shell_win.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 "content/shell/browser/shell.h"
 
 #include <windows.h>
 #include <commctrl.h>
 #include <fcntl.h>
 #include <io.h>
@@ skipping 260 matching lines @@
         }
 
         return 0;
       }
   }
 
   return CallWindowProc(shell->default_edit_wnd_proc_, hwnd, message, wParam,
                         lParam);
 }
 
-void Shell::PlatformSetTitle(const string16& text) {
+void Shell::PlatformSetTitle(const base::string16& text) {
   ::SetWindowText(window_, text.c_str());
 }
 
 }  // namespace content