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

chrome/browser/ui/app_list/search/history.cc

 // Copyright 2013 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/ui/app_list/search/history.h"
 
 #include "base/files/file_path.h"
-#include "base/string_util.h"
+#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/ui/app_list/search/history_data.h"
 #include "chrome/browser/ui/app_list/search/history_data_store.h"
 #include "chrome/browser/ui/app_list/search/tokenized_string.h"
 #include "content/public/browser/browser_context.h"
 
 namespace app_list {
 
 namespace {
 
@@ skipping 37 matching lines @@
     const std::string& query) const {
   DCHECK(IsReady());
   return data_->GetKnownResults(NormalizeString(query)).Pass();
 }
 
 void History::OnHistoryDataLoadedFromStore() {
   data_loaded_ = true;
 }
 
 }  // namespace app_list