Template methods on Timer classes instead of the classes themselves.

ash/system/tray_update.cc

Index: ash/system/tray_update.cc
diff --git a/ash/system/tray_update.cc b/ash/system/tray_update.cc
index d24a6e998b42d2b5e5770227770b3364388ed44b..5b67baee94365f717af56acce210a83778f69ea2 100644
--- a/ash/system/tray_update.cc
+++ b/ash/system/tray_update.cc
@@ -150,7 +150,7 @@ class UpdateNagger : public ui::LayerAnimationObserver {
       ui::LayerAnimationSequence* sequence) override {}
 
   SystemTrayItem* owner_;
-  base::OneShotTimer<UpdateNagger> timer_;
+  base::OneShotTimer timer_;
 
   DISALLOW_COPY_AND_ASSIGN(UpdateNagger);
 };