Introduce SystemMenuButton for Ash material design

ash/common/system/tray/system_menu_button.h

Index: ash/common/system/tray/system_menu_button.h
diff --git a/ash/common/system/tray/system_menu_button.h b/ash/common/system/tray/system_menu_button.h
new file mode 100644
index 0000000000000000000000000000000000000000..0256017800410eba85b93f61ec9bc90306dd7544
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+++ b/ash/common/system/tray/system_menu_button.h
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+// Copyright 2016 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_COMMON_SYSTEM_TRAY_SYSTEM_MENU_BUTTON_H_
+#define ASH_COMMON_SYSTEM_TRAY_SYSTEM_MENU_BUTTON_H_
+
+#include "ash/resources/vector_icons/vector_icons.h"
+#include "base/macros.h"
+#include "ui/views/controls/button/button.h"
+#include "ui/views/controls/button/image_button.h"
+
+namespace views {
+class InkDropHighlight;
+class InkDropRipple;
+}
+
+namespace ash {
+
+// A 48x48 image button with a material design ripple effect, which can be
+// used across Ash material design native UI menus.
+// TODO(tdanderson): Deprecate TrayPopupHeaderButton in favor of
+// SystemMenuButton once material design is enabled by default. See
+// crbug.com/614453.
+class SystemMenuButton : public views::ImageButton {
+ public:
+  // Constructs the button with |listener| and a centered icon corresponding to
+  // |icon|. |accessible_name_id| corresponds to the string in
+  // ui::ResourceBundle to use for the button's accessible and tooltip text.
+  SystemMenuButton(views::ButtonListener* listener,
+                   const gfx::VectorIcon& icon,
+                   int accessible_name_id);
+  ~SystemMenuButton() override;
+
+  // views::ImageButton:
+  std::unique_ptr<views::InkDropRipple> CreateInkDropRipple() const override;
+  std::unique_ptr<views::InkDropHighlight> CreateInkDropHighlight()
+      const override;
+  bool ShouldShowInkDropForFocus() const override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SystemMenuButton);
+};
+
+}  // namespace ash
+
+#endif  // ASH_COMMON_SYSTEM_TRAY_SYSTEM_MENU_BUTTON_H_