Uses WeakPtrFactory instead of base::Unretained.

ash/system/ime/tray_ime.h

Index: ash/system/ime/tray_ime.h
diff --git a/ash/system/ime/tray_ime.h b/ash/system/ime/tray_ime.h
index b237ae15abc116981ed986263a754814a2610a39..bb65e990f1553026d0fa0d7abd2be406be31f577 100644
--- a/ash/system/ime/tray_ime.h
+++ b/ash/system/ime/tray_ime.h
@@ -7,6 +7,7 @@
 
 #include "ash/system/ime/ime_observer.h"
 #include "ash/system/tray/system_tray_item.h"
+#include "base/memory/weak_ptr.h"
 
 namespace views {
 class Label;
@@ -61,6 +62,8 @@ class TrayIME : public SystemTrayItem,
 
   bool message_shown_;
 
+  base::WeakPtrFactory<TrayIME> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(TrayIME);
 };