WIP: PointerWatcher for systray bubble

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 df447a5fb38370cd156919e65b88573bfc696ed6..1cef6d9a36883a1374e9908f613b2fc5adf18136 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);