Use a direct include of strings headers in ui/, part 1.

ui/app_list/app_list_view_delegate.h

 // 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.
 
 #ifndef UI_APP_LIST_APP_LIST_VIEW_DELEGATE_H_
 #define UI_APP_LIST_APP_LIST_VIEW_DELEGATE_H_
 
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "ui/app_list/app_list_export.h"
 
 namespace gfx {
 class ImageSkia;
 }
 
 namespace app_list {
 
 class AppListItemModel;
 class AppListModel;
@@ skipping 58 matching lines @@
   // Open the help UI.
   virtual void OpenHelp() = 0;
 
   // Open the feedback UI.
   virtual void OpenFeedback() = 0;
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_APP_LIST_VIEW_DELEGATE_H_