WIP: PointerWatcher for systray bubble

ash/system/tray/system_tray.cc

Index: ash/system/tray/system_tray.cc
diff --git a/ash/system/tray/system_tray.cc b/ash/system/tray/system_tray.cc
index 6be418a7d7aa118e1e11423cb3a0535a09d070d3..bb0ddf429fe391d32b6afd25c90a24c476e3c063 100644
--- a/ash/system/tray/system_tray.cc
+++ b/ash/system/tray/system_tray.cc
@@ -653,11 +653,10 @@ void SystemTray::HideBubbleWithView(const TrayBubbleView* bubble_view) {
   }
 }
 
-bool SystemTray::ClickedOutsideBubble() {
+void SystemTray::ClickedOutsideBubble() {
   if (!system_bubble_ || system_bubble_->is_persistent())
-    return false;
+    return;
   HideBubbleWithView(system_bubble_->bubble_view());
-  return true;
 }
 
 void SystemTray::BubbleViewDestroyed() {