mash: Close the system tray bubble on click outside its bounds

ash/system/tray/tray_background_view.h

Index: ash/system/tray/tray_background_view.h
diff --git a/ash/system/tray/tray_background_view.h b/ash/system/tray/tray_background_view.h
index e908cb34f41f3914095715ef80f78411285bf126..ecf8404441efcf8c0a47d6211f18df6964f96a74 100644
--- a/ash/system/tray/tray_background_view.h
+++ b/ash/system/tray/tray_background_view.h
@@ -102,8 +102,8 @@ class ASH_EXPORT TrayBackgroundView : public ActionableView,
   virtual void HideBubbleWithView(const views::TrayBubbleView* bubble_view) = 0;
 
   // Called by the bubble wrapper when a click event occurs outside the bubble.
-  // May close the bubble. Returns true if the event is handled.
-  virtual bool ClickedOutsideBubble() = 0;
+  // May close the bubble.
+  virtual void ClickedOutsideBubble() = 0;
 
   // Sets |contents| as a child.
   void SetContents(views::View* contents);