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

chrome/browser/autocomplete/extension_app_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/extension_app_provider.h"
 
 #include <algorithm>
 #include <cmath>
 
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/extension_system_factory.h"
 #include "chrome/browser/history/history_service.h"
 #include "chrome/browser/history/history_service_factory.h"
 #include "chrome/browser/history/url_database.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/extensions/application_launch.h"
 #include "chrome/browser/ui/webui/ntp/app_launcher_handler.h"
 #include "chrome/common/chrome_notification_types.h"
@@ skipping 195 matching lines @@
     history::URLRow info;
     url_db->GetRowForURL(url, &info);
     type_count_boost =
         400 * (1.0 - (std::pow(static_cast<double>(2), -info.typed_count())));
   }
   int relevance = 575 + static_cast<int>(type_count_boost) +
                         static_cast<int>(fraction_boost);
   DCHECK_LE(relevance, kMaxRelevance);
   return relevance;
 }