Update chromeos system menu buttons for MD.

ash/common/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_COMMON_SYSTEM_TRAY_TRAY_UTILS_H_
 #define ASH_COMMON_SYSTEM_TRAY_TRAY_UTILS_H_
 
 #include <vector>
 
 #include "ash/common/login_status.h"
 #include "ash/public/cpp/shelf_types.h"
 #include "base/strings/string16.h"
 
 namespace views {
+class ButtonListener;
 class Label;
+class LabelButton;
 class Separator;
 class View;
 }
 
 namespace ash {
 
 class TrayItemView;
 
+// Creates a button for use in the system menu that has no visible border when

[tdanderson, 2016/11/01 22:38:50]

nit: please add a comment that the caller assumes ownership of the returned
button (here and for CreateTrayPopupButton())

[Evan Stade, 2016/11/01 23:54:09]

I have a hard time seeing how one would reasonably conclude otherwise... but
done.

+// not being hovered/clicked.

[tdanderson, 2016/11/01 22:38:50]

nit: consider eliminating the double negative in the documentation such as "only
has a visible border when hovered/clicked"

[Evan Stade, 2016/11/01 23:54:09]

Done.

+views::LabelButton* CreateTrayPopupBorderlessButton(
+    views::ButtonListener* listener,
+    const base::string16& text);
+
+// Creates a button for use in the system menu. For non-MD, this does the same

[tdanderson, 2016/11/01 22:38:50]

nit: please give a bit more description about what happens for MD (i.e.,
"creates a material design text button" and list any visual properties)

[Evan Stade, 2016/11/01 23:54:09]

Done.

+// thing as the above.
+views::LabelButton* CreateTrayPopupButton(views::ButtonListener* listener,
+                                          const base::string16& text);
+
 // 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);
@@ skipping 10 matching lines @@
 bool CanOpenWebUISettings(LoginStatus status);
 
 // Creates and returns a vertical separator to be used between two items in a
 // material design system menu row. The caller assumes ownership of the
 // returned separator.
 views::Separator* CreateVerticalSeparator();
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_TRAY_TRAY_UTILS_H_