Minimal support for OOBE/login for chrome-athena

chrome/browser/chromeos/login/ui/input_events_blocker.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 "chrome/browser/chromeos/login/ui/input_events_blocker.h"
 
 #include "ash/shell.h"
 #include "base/logging.h"
 #include "ui/events/event.h"
 
 namespace chromeos {
 
 InputEventsBlocker::InputEventsBlocker() {
-  ash::Shell::GetInstance()->PrependPreTargetHandler(this);
+  if (ash::Shell::HasInstance())
+    ash::Shell::GetInstance()->PrependPreTargetHandler(this);
   VLOG(1) << "InputEventsBlocker " << this << " created.";
 }
 
 InputEventsBlocker::~InputEventsBlocker() {
-  ash::Shell::GetInstance()->RemovePreTargetHandler(this);
+  if (ash::Shell::HasInstance())
+    ash::Shell::GetInstance()->RemovePreTargetHandler(this);
   VLOG(1) << "InputEventsBlocker " << this << " destroyed.";
 }
 
 void InputEventsBlocker::OnKeyEvent(ui::KeyEvent* event) {
   event->StopPropagation();
 }
 
 void InputEventsBlocker::OnMouseEvent(ui::MouseEvent* event) {
   event->StopPropagation();
 }
 
 void InputEventsBlocker::OnTouchEvent(ui::TouchEvent* event) {
   event->StopPropagation();
 }
 
 void InputEventsBlocker::OnGestureEvent(ui::GestureEvent* event) {
   event->StopPropagation();
 }
 
 }  // namespace chromeos