Use a direct include of strings headers in chrome/auto*/.

chrome/browser/autocomplete/zero_suggest_provider.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/autocomplete/zero_suggest_provider.h"
 
 #include "base/callback.h"
 #include "base/i18n/case_conversion.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/metrics/histogram.h"
 #include "base/prefs/pref_service.h"
-#include "base/string16.h"
-#include "base/string_util.h"
+#include "base/strings/string16.h"
+#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/time.h"
 #include "chrome/browser/autocomplete/autocomplete_input.h"
 #include "chrome/browser/autocomplete/autocomplete_match.h"
 #include "chrome/browser/autocomplete/autocomplete_provider_listener.h"
 #include "chrome/browser/autocomplete/history_url_provider.h"
 #include "chrome/browser/autocomplete/search_provider.h"
 #include "chrome/browser/autocomplete/url_prefix.h"
 #include "chrome/browser/metrics/variations/variations_http_header_provider.h"
 #include "chrome/browser/net/url_fixer_upper.h"
@@ skipping 455 matching lines @@
       HistoryURLProvider::SuggestExactInput(this, input, true));
   match.is_history_what_you_typed_match = false;
 
   // The placeholder suggestion for the current URL has high relevance so
   // that it is in the first suggestion slot and inline autocompleted. It
   // gets dropped as soon as the user types something.
   match.relevance = verbatim_relevance_;
 
   return match;
 }