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

ash/common/system/status_area_widget.h

Index: ash/common/system/status_area_widget.h
diff --git a/ash/common/system/status_area_widget.h b/ash/common/system/status_area_widget.h
index 9ee9143f9ce1fdb6a16801891a727810208bba0b..8b27200309c7312edaa8a7632a8e2dce3e80ba44 100644
--- a/ash/common/system/status_area_widget.h
+++ b/ash/common/system/status_area_widget.h
@@ -17,6 +17,7 @@ class OverviewButtonTray;
 class ShellDelegate;
 class StatusAreaWidgetDelegate;
 class SystemTray;
+class TrayBackgroundView;
 class WebNotificationTray;
 class WmShelf;
 class WmWindow;
@@ -48,6 +49,12 @@ class ASH_EXPORT StatusAreaWidget : public views::Widget,
   // notification tray.
   void UpdateAfterLoginStatusChange(LoginStatus login_status);
 
+  // Based on visibility of |tray| and tray item on its right, sets |tray|'s

[varkha, 2016/08/11 20:01:03]

nit: s/and tray item/and a tray item

[yiyix, 2016/08/18 00:43:00]

Done.

+  // separator visibility either to true or false. Note that no leading
+  // separator is required before the logout_button_tray because that
+  // button's red background is distinctive on its own.
+  void OnTrayVisibilityChanged(TrayBackgroundView* tray);
+
   StatusAreaWidgetDelegate* status_area_widget_delegate() {
     return status_area_widget_delegate_;
   }
@@ -91,6 +98,10 @@ class ASH_EXPORT StatusAreaWidget : public views::Widget,
   void AddPaletteTray();
   void AddVirtualKeyboardTray();
   void AddImeMenuTray();
+
+  // Check if |tray| is next visible tray to the |logout_button_tray_|. If

[James Cook, 2016/08/11 20:36:55]

nit: By "next visible tray" do you mean next in the view child list? Or on the
right? On the left?

[yiyix, 2016/08/18 00:43:00]

I mean it is next in the view child list, so it displays as left view to
logout_button_tray_ in chrome os system. 

+  // |logout_button_tray_| is not visible, then it returns false.
+  bool IsNextVisibleTrayToLogout(TrayBackgroundView* tray);
 #endif
   void AddOverviewButtonTray();