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

extensions/common/error_utils.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.
 
 #include "extensions/common/error_utils.h"
 
-#include "base/string_util.h"
+#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 
 namespace extensions {
 
 std::string ErrorUtils::FormatErrorMessage(const std::string& format,
                                            const std::string& s1) {
   std::string ret_val = format;
   ReplaceFirstSubstringAfterOffset(&ret_val, 0, "*", s1);
   return ret_val;
 }
@@ skipping 39 matching lines @@
                                              const std::string& s2,
                                              const std::string& s3) {
   std::string ret_val = format;
   ReplaceFirstSubstringAfterOffset(&ret_val, 0, "*", s1);
   ReplaceFirstSubstringAfterOffset(&ret_val, 0, "*", s2);
   ReplaceFirstSubstringAfterOffset(&ret_val, 0, "*", s3);
   return UTF8ToUTF16(ret_val);
 }
 
 }  // namespace