ash: Fix event processing in modal windows in login/lock screen.

ash/wm/shelf_layout_manager.cc

 // Copyright (c) 2012 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/wm/shelf_layout_manager.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "ash/ash_switches.h"
@@ skipping 849 matching lines @@
     return AUTO_HIDE_SHOWN;
 
   if (launcher_widget()->IsActive() || status_->IsActive())
     return AUTO_HIDE_SHOWN;
 
   // Don't show if the user is dragging the mouse.
   if (event_filter_.get() && event_filter_->in_mouse_drag())
     return AUTO_HIDE_HIDDEN;
 
   gfx::Rect shelf_region = launcher_widget()->GetWindowBoundsInScreen();
-  if (Shell::GetInstance()->status_area_widget()->IsMessageBubbleShown() &&
+  if (shell->status_area_widget() &&
+      shell->status_area_widget()->IsMessageBubbleShown() &&
       IsVisible()) {
     // Increase the the hit test area to prevent the shelf from disappearing
     // when the mouse is over the bubble gap.
     shelf_region.Inset(alignment_ == SHELF_ALIGNMENT_RIGHT ?
                            -kNotificationBubbleGapHeight : 0,
                        alignment_ == SHELF_ALIGNMENT_BOTTOM ?
                            -kNotificationBubbleGapHeight : 0,
                        alignment_ == SHELF_ALIGNMENT_LEFT ?
                            -kNotificationBubbleGapHeight : 0,
                        0);
@@ skipping 39 matching lines @@
 int ShelfLayoutManager::GetWorkAreaSize(const State& state, int size) const {
   if (state.visibility_state == VISIBLE)
     return size;
   if (state.visibility_state == AUTO_HIDE)
     return kAutoHideSize;
   return 0;
 }
 
 }  // namespace internal
 }  // namespace ash