Change base::TickClock to a ref counted class.

ash/system/chromeos/session/logout_confirmation_controller.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/system/chromeos/session/logout_confirmation_controller.h"
 
 #include "ash/session/session_state_delegate.h"
 #include "ash/shell.h"
 #include "ash/system/chromeos/session/logout_confirmation_dialog.h"
 #include "base/location.h"
@@ skipping 37 matching lines @@
   } else {
     dialog_->Update(logout_time_);
   }
 
   logout_timer_.Start(FROM_HERE,
                       logout_time_ - clock_->NowTicks(),
                       logout_closure_);
 }
 
 void LogoutConfirmationController::SetClockForTesting(
-    scoped_ptr<base::TickClock> clock) {
-  clock_ = clock.Pass();
+    const scoped_refptr<base::TickClock>& clock) {
+  clock_ = clock;
 }
 
 void LogoutConfirmationController::OnLockStateChanged(bool locked) {
   if (!locked || logout_time_.is_null())
     return;
 
   // If the screen is locked while a confirmation dialog is being shown, close
   // the dialog.
   logout_time_ = base::TimeTicks();
   if (dialog_)
     dialog_->GetWidget()->Close();
   logout_timer_.Stop();
 }
 
 void LogoutConfirmationController::OnLogoutConfirmed() {
   logout_timer_.Stop();
   logout_closure_.Run();
 }
 
 void LogoutConfirmationController::OnDialogClosed() {
   logout_time_ = base::TimeTicks();
   dialog_ = NULL;
   logout_timer_.Stop();
 }
 
 }  // namespace ash