Revert of mus: Rename .*PointerWatcher.* to .*PointerDownWatcher.*.

ash/common/system/tray/tray_event_filter.cc

Index: ash/common/system/tray/tray_event_filter.cc
diff --git a/ash/common/system/tray/tray_event_filter.cc b/ash/common/system/tray/tray_event_filter.cc
index 6d98214d0036f216869716e8b67f19fcfb7dba98..3b277ccf184456965bfa1ee9e23c71eec44d9635 100644
--- a/ash/common/system/tray/tray_event_filter.cc
+++ b/ash/common/system/tray/tray_event_filter.cc
@@ -25,13 +25,13 @@ void TrayEventFilter::AddWrapper(TrayBubbleWrapper* wrapper) {
   bool was_empty = wrappers_.empty();
   wrappers_.insert(wrapper);
   if (was_empty && !wrappers_.empty())
-    WmShell::Get()->AddPointerDownWatcher(this);
+    WmShell::Get()->AddPointerWatcher(this);
 }
 
 void TrayEventFilter::RemoveWrapper(TrayBubbleWrapper* wrapper) {
   wrappers_.erase(wrapper);
   if (wrappers_.empty())
-    WmShell::Get()->RemovePointerDownWatcher(this);
+    WmShell::Get()->RemovePointerWatcher(this);
 }
 
 void TrayEventFilter::OnMousePressed(const ui::MouseEvent& event,