Use a direct include of strings headers in chrome/browser/a*-c*/.

chrome/browser/content_settings/host_content_settings_map.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/browser/content_settings/host_content_settings_map.h"
 
 #include <utility>
 
 #include "base/basictypes.h"
 #include "base/command_line.h"
 #include "base/prefs/pref_service.h"
 #include "base/stl_util.h"
-#include "base/string_util.h"
+#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/content_settings/content_settings_custom_extension_provider.h"
 #include "chrome/browser/content_settings/content_settings_default_provider.h"
 #include "chrome/browser/content_settings/content_settings_details.h"
 #include "chrome/browser/content_settings/content_settings_internal_extension_provider.h"
 #include "chrome/browser/content_settings/content_settings_observable_provider.h"
 #include "chrome/browser/content_settings/content_settings_policy_provider.h"
 #include "chrome/browser/content_settings/content_settings_pref_provider.h"
 #include "chrome/browser/content_settings/content_settings_provider.h"
 #include "chrome/browser/content_settings/content_settings_rule.h"
@@ skipping 578 matching lines @@
     HostContentSettingsMap::GetProviderTypeFromSource(
         const std::string& source) {
   for (size_t i = 0; i < arraysize(kProviderNames); ++i) {
     if (source == kProviderNames[i])
       return static_cast<ProviderType>(i);
   }
 
   NOTREACHED();
   return DEFAULT_PROVIDER;
 }