[Chrome OS MD] Draw a 1px separator between 2 tray items

ash/common/system/overview/overview_button_tray.h

 // Copyright 2014 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_OVERVIEW_OVERVIEW_BUTTON_TRAY_H_
 #define ASH_COMMON_SYSTEM_OVERVIEW_OVERVIEW_BUTTON_TRAY_H_
 
 #include "ash/ash_export.h"
 #include "ash/common/session/session_state_observer.h"
 #include "ash/common/shell_observer.h"
@@ skipping 39 matching lines @@
   void HideBubbleWithView(const views::TrayBubbleView* bubble_view) override;
   void SetShelfAlignment(ShelfAlignment alignment) override;
 
  private:
   friend class OverviewButtonTrayTest;
 
   // Creates a new border for the icon. The padding is determined based on the
   // alignment of the shelf.
   void SetIconBorderForShelfAlignment();
 
+  // Additional padding are used to adjust the user-visible size of overview

[varkha, 2016/07/14 21:34:47]

nit: s/are/is
More importantly the comment should say what the method does so how about:
Sets an empty border around the overview tray to change user-visible size of the
dark background. Doesn't do anything in non-MD.

[yiyix, 2016/07/26 20:27:31]

Done.

+  // button tray dark background in non-MD.
+  void AdjustOverviewBackground();

[varkha, 2016/07/14 21:34:47]

Maybe SetOverviewTrayBorder() ?

[yiyix, 2016/07/26 20:27:31]

Sure, SetOverviewTrayBorder() is more about what the function does.

+
   // Sets the icon to visible if maximize mode is enabled and
   // WindowSelectorController::CanSelect.
   void UpdateIconVisibility();
 
   // Weak pointer, will be parented by TrayContainer for its lifetime.
   views::ImageView* icon_;
 
   DISALLOW_COPY_AND_ASSIGN(OverviewButtonTray);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_OVERVIEW_OVERVIEW_BUTTON_TRAY_H_