Uses WeakPtrFactory instead of base::Unretained.

Although TrayIME removes the notification, the callback notification
delegate may survive due to complicated ref-counted-ness of
NotificationDelegate.

Anyways WeakPtr would be better here rather than Unretained.

BUG=336650
R=stevenjb@chromium.org, dewittj@chromium.org
TEST=None

Review URL: https://codereview.chromium.org/138833004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248577 0039d316-1c4b-4281-b951-d872f2087c98

ash/system/ime/tray_ime.cc

@@ -190,7 +190,8 @@ TrayIME::TrayIME(SystemTray* system_tray)
       tray_label_(NULL),
       default_(NULL),
       detailed_(NULL),
-      message_shown_(false) {
+      message_shown_(false),
+      weak_factory_(this) {
   Shell::GetInstance()->system_tray_notifier()->AddIMEObserver(this);
 }
 
@@ -243,7 +244,7 @@ void TrayIME::UpdateOrCreateNotification() {
       message_center::RichNotificationData(),
       new message_center::HandleNotificationClickedDelegate(
           base::Bind(&TrayIME::PopupDetailedView,
-                     base::Unretained(this), 0, true))));
+                     weak_factory_.GetWeakPtr(), 0, true))));
   message_center->AddNotification(notification.Pass());
   message_shown_ = true;
 }

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);
 };