WIP: Eliminate event.target() usage from TrayEventFilter

ash/system/tray/tray_event_filter.h

Index: ash/system/tray/tray_event_filter.h
diff --git a/ash/system/tray/tray_event_filter.h b/ash/system/tray/tray_event_filter.h
index c38dd2b23a0f931f9b5ab0f11df0eefc0333e28c..f9a33c7c3af207cbf41c7817097a67ed2263fe88 100644
--- a/ash/system/tray/tray_event_filter.h
+++ b/ash/system/tray/tray_event_filter.h
@@ -33,13 +33,16 @@ class TrayEventFilter : public views::PointerWatcher {
 
   // views::PointerWatcher:
   void OnMousePressed(const ui::MouseEvent& event,
-                      const gfx::Point& location_in_screen) override;
+                      const gfx::Point& location_in_screen,
+                      views::Widget* target) override;
   void OnTouchPressed(const ui::TouchEvent& event,
-                      const gfx::Point& location_in_screen) override;
+                      const gfx::Point& location_in_screen,
+                      views::Widget* target) override;
 
  private:
-  void ProcessLocatedEvent(const ui::LocatedEvent& event,
-                           const gfx::Point& location_in_screen);
+  void ProcessPressedEvent(const ui::LocatedEvent& event,
+                           const gfx::Point& location_in_screen,
+                           views::Widget* target);
 
   std::set<TrayBubbleWrapper*> wrappers_;