[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 562949612f0d98903f2ac0f73c4e0a6495a4c91b..e2896bb0634c661f0f85c43b712f91229ecf928e 100644
--- a/ash/common/system/status_area_widget.h
+++ b/ash/common/system/status_area_widget.h
@@ -9,6 +9,7 @@
 #include "ash/common/login_status.h"
 #include "ash/common/shelf/shelf_background_animator_observer.h"
 #include "ash/common/shelf/shelf_types.h"
+#include "ash/common/shelf/wm_shelf_observer.h"
 #include "base/macros.h"
 #include "ui/views/widget/widget.h"
 
@@ -17,6 +18,7 @@ class OverviewButtonTray;
 class ShellDelegate;
 class StatusAreaWidgetDelegate;
 class SystemTray;
+class TrayBackgroundView;
 class WebNotificationTray;
 class WmShelf;
 class WmWindow;
@@ -28,7 +30,8 @@ class VirtualKeyboardTray;
 #endif
 
 class ASH_EXPORT StatusAreaWidget : public views::Widget,
-                                    public ShelfBackgroundAnimatorObserver {
+                                    public ShelfBackgroundAnimatorObserver,
+                                    public WmShelfObserver {
  public:
   StatusAreaWidget(WmWindow* status_container, WmShelf* wm_shelf);
   ~StatusAreaWidget() override;
@@ -85,6 +88,12 @@ class ASH_EXPORT StatusAreaWidget : public views::Widget,
   // ShelfBackgroundAnimatorObserver:
   void UpdateShelfItemBackground(int alpha) override;
 
+  // Based on visibility of |tray| and tray item on its right, it sets |tray|'s

[varkha, 2016/08/10 23:27:24]

nit: remove "it" (in "it sets |tray|'s ...").

[yiyix, 2016/08/11 01:23:18]

Done.

+  // visibility of the separator 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 OnVisibilityChange(TrayBackgroundView* tray) override;

[James Cook, 2016/08/09 00:25:17]

nit: put "WmShelfObserver:" above this line and move the rest of the comment
into the .cc file

[yiyix, 2016/08/11 01:23:19]

Done.

+
  private:
   void AddSystemTray();
   void AddWebNotificationTray();