Use a direct include of strings headers in extensions/, google_apis/, gpu/.

gpu/command_buffer/service/feature_info.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 "gpu/command_buffer/service/feature_info.h"
 
 #include <set>
 
 #include "base/command_line.h"
-#include "base/string_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
+#include "base/strings/string_util.h"
 #include "gpu/command_buffer/service/gl_utils.h"
 #include "gpu/command_buffer/service/gpu_switches.h"
 #include "ui/gl/gl_implementation.h"
 #if defined(OS_MACOSX)
 #include "ui/surface/io_surface_support_mac.h"
 #endif
 
 namespace gpu {
 namespace gles2 {
 
@@ skipping 620 matching lines @@
   if (extensions_.find(str) == std::string::npos) {
     extensions_ += (extensions_.empty() ? "" : " ") + str;
   }
 }
 
 FeatureInfo::~FeatureInfo() {
 }
 
 }  // namespace gles2
 }  // namespace gpu