Use a direct include of strings headers in content/browser/, part 1.

content/browser/geolocation/wifi_data_provider_common_unittest.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 <vector>
 
 #include "base/memory/scoped_ptr.h"
-#include "base/string_util.h"
+#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/third_party/dynamic_annotations/dynamic_annotations.h"
 #include "content/browser/geolocation/wifi_data_provider_common.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 using testing::_;
 using testing::AtLeast;
 using testing::DoDefault;
 using testing::Invoke;
@@ skipping 205 matching lines @@
        StartThreadViaDeviceDataProvider) {
   MessageLoopQuitListener quit_listener(&main_message_loop_);
   WifiDataProvider::SetFactory(CreateWifiDataProviderCommonWithMock);
   DeviceDataProvider<WifiData>::Register(&quit_listener);
   main_message_loop_.Run();
   DeviceDataProvider<WifiData>::Unregister(&quit_listener);
   DeviceDataProvider<WifiData>::ResetFactory();
 }
 
 }  // namespace content