Set NULL if before releasing IBusUiController instance.

chrome/browser/chromeos/input_method/candidate_window_controller_impl.cc

Index: chrome/browser/chromeos/input_method/candidate_window_controller_impl.cc
diff --git a/chrome/browser/chromeos/input_method/candidate_window_controller_impl.cc b/chrome/browser/chromeos/input_method/candidate_window_controller_impl.cc
index 0462400aa284f9068a4a09d52e64dcc59e4ebf19..360e2ff8f4281538a18568844bd78e0706ceea2e 100644
--- a/chrome/browser/chromeos/input_method/candidate_window_controller_impl.cc
+++ b/chrome/browser/chromeos/input_method/candidate_window_controller_impl.cc
@@ -102,6 +102,9 @@ CandidateWindowControllerImpl::CandidateWindowControllerImpl()
 }
 
 CandidateWindowControllerImpl::~CandidateWindowControllerImpl() {
+  if (DBusThreadManager::Get()->GetIBusPanelService())
+    DBusThreadManager::Get()->GetIBusPanelService()->
+        SetUpCandidateWindowHandler(NULL);
   ibus_ui_controller_->RemoveObserver(this);
   candidate_window_->RemoveObserver(this);
   // ibus_ui_controller_'s destructor will close the connection.