Use a direct include of strings headers in chrome_frame/.

chrome_frame/test/win_event_receiver.cc

 // Copyright (c) 2012 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_frame/test/win_event_receiver.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop.h"
+#include "base/strings/string_util.h"
 #include "base/win/object_watcher.h"
-#include "base/string_util.h"
 #include "chrome_frame/function_stub.h"
 
 // WinEventReceiver methods
 WinEventReceiver::WinEventReceiver()
     : listener_(NULL),
       hook_(NULL),
       hook_stub_(NULL) {
 }
 
 WinEventReceiver::~WinEventReceiver() {
@@ skipping 243 matching lines @@
     HandleOnOpen(hwnd);
   } else {
     DCHECK(event == EVENT_OBJECT_DESTROY || event == EVENT_OBJECT_HIDE);
     HandleOnClose(hwnd);
   }
 }
 
 void WindowWatchdog::OnHwndProcessExited(HWND hwnd) {
   HandleOnClose(hwnd);
 }