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

ui/base/accelerators/accelerator.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.
 
 // This class describe a keyboard accelerator (or keyboard shortcut).
 // Keyboard accelerators are registered with the FocusManager.
 // It has a copy constructor and assignment operator so that it can be copied.
 // It also defines the < operator so that it can be used as a key in a std::map.
 //
 
 #ifndef UI_BASE_ACCELERATORS_ACCELERATOR_H_
 #define UI_BASE_ACCELERATORS_ACCELERATOR_H_
 
 #include "base/memory/scoped_ptr.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "ui/base/accelerators/platform_accelerator.h"
 #include "ui/base/events/event_constants.h"
 #include "ui/base/keycodes/keyboard_codes.h"
 #include "ui/base/ui_export.h"
 
 namespace ui {
 
 class PlatformAccelerator;
 
 // This is a cross-platform class for accelerator keys used in menus.
@@ skipping 82 matching lines @@
   virtual bool GetAcceleratorForCommandId(int command_id,
                                           ui::Accelerator* accelerator) = 0;
 
  protected:
   virtual ~AcceleratorProvider() {}
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_ACCELERATORS_ACCELERATOR_H_