Use a direct include of strings headers in webkit/, part 2.

webkit/plugins/npapi/test/plugin_thread_async_call_test.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.
 
 #define UNIT_TEST  // To get the ShadowingAtExitManager.
 #include "base/at_exit.h"
 
 #include "webkit/plugins/npapi/test/plugin_thread_async_call_test.h"
 
 #include "base/bind.h"
 #include "base/message_loop.h"
-#include "base/string_util.h"
+#include "base/strings/string_util.h"
 #include "base/threading/thread.h"
 #include "webkit/plugins/npapi/test/plugin_client.h"
 
 namespace NPAPIClient {
 
 namespace {
 
 // There are two plugin instances in this test. The long lived instance is used
 // for reporting errors and signalling test completion. The short lived one is
 // used to verify that async callbacks are not invoked after NPP_Destroy.
@@ skipping 85 matching lines @@
   }
 
   return NPERR_NO_ERROR;
 }
 
 void PluginThreadAsyncCallTest::OnCallCompleted() {
   SignalTestCompleted();
 }
 
 }  // namespace NPAPIClient