Checked validity of status_widget before calling IsActive method.

ash/shelf/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/shelf/shelf_layout_manager.h"
 
 #include <algorithm>
 #include <cmath>
 #include <cstring>
 #include <string>
@@ skipping 1010 matching lines @@
   if (shelf_->status_area_widget() &&
       shelf_->status_area_widget()->ShouldShowShelf())
     return SHELF_AUTO_HIDE_SHOWN;
 
   if (shelf_->shelf() && shelf_->shelf()->IsShowingMenu())
     return SHELF_AUTO_HIDE_SHOWN;
 
   if (shelf_->shelf() && shelf_->shelf()->IsShowingOverflowBubble())
     return SHELF_AUTO_HIDE_SHOWN;
 
-  if (shelf_->IsActive() || shelf_->status_area_widget()->IsActive())
+  if (shelf_->IsActive() ||
+      (shelf_->status_area_widget() &&
+       shelf_->status_area_widget()->IsActive()))
     return SHELF_AUTO_HIDE_SHOWN;
 
   const std::vector<aura::Window*> windows =
       ash::MruWindowTracker::BuildWindowList(false);
 
   // Process the window list and check if there are any visible windows.
   bool visible_window = false;
   for (size_t i = 0; i < windows.size(); ++i) {
     if (windows[i] && windows[i]->IsVisible() &&
         !wm::GetWindowState(windows[i])->IsMinimized() &&
@@ skipping 136 matching lines @@
 
 void ShelfLayoutManager::SessionStateChanged(
     SessionStateDelegate::SessionState state) {
   TargetBounds target_bounds;
   CalculateTargetBounds(state_, &target_bounds);
   UpdateBoundsAndOpacity(target_bounds, true, NULL);
   UpdateVisibilityState();
 }
 
 }  // namespace ash