mash: Move SystemTrayImage and TrayImageItem to //ash/common

ash/system/tray/tray_utils.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 ASH_SYSTEM_TRAY_TRAY_UTILS_H_
-#define ASH_SYSTEM_TRAY_TRAY_UTILS_H_
-
-#include <vector>
-
-#include "ash/common/shelf/shelf_types.h"
-#include "base/strings/string16.h"
-
-namespace views {
-class Label;
-class View;
-}
-
-namespace ash {
-
-class TrayItemView;
-
-// Sets up a Label properly for the tray (sets color, font etc.).
-void SetupLabelForTray(views::Label* label);
-
-// TODO(jennyz): refactor these two functions to SystemTrayItem.
-// Sets the empty border of an image tray item for adjusting the space
-// around it.
-void SetTrayImageItemBorder(views::View* tray_view, ShelfAlignment alignment);
-// Sets the empty border around a label tray item for adjusting the space
-// around it.
-void SetTrayLabelItemBorder(TrayItemView* tray_view, ShelfAlignment alignment);
-
-// Computes an accessible label for this button based on all descendant view
-// labels by concatenating them in depth-first order.
-void GetAccessibleLabelFromDescendantViews(
-    views::View* view,
-    std::vector<base::string16>& out_labels);
-
-}  // namespace ash
-
-#endif  // ASH_SYSTEM_TRAY_TRAY_UTILS_H_