Accessibility manager shouldn't try to access ash Shelf from login screen.

chrome/browser/chromeos/accessibility/accessibility_manager.h

 // Copyright (c) 2013 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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_ACCESSIBILITY_MANAGER_H_
 #define CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_ACCESSIBILITY_MANAGER_H_
 
 #include <set>
 
 #include "ash/session/session_state_observer.h"
@@ skipping 224 matching lines @@
 
   // Plays an earcon. Earcons are brief and distinctive sounds that indicate
   // when their mapped event has occurred. The sound key enums can be found in
   // chromeos/audio/chromeos_sounds.h.
   void PlayEarcon(int sound_key);
 
   // Called by our widget observer when the ChromeVoxPanel is closing.
   void OnChromeVoxPanelClosing();
   void OnChromeVoxPanelDestroying();
 
+  // Called when switching profiles so we can make sure the panel height
+  // is set.
+  void UpdateChromeVoxPanelHeight();
+
   // Profile having the a11y context.
   Profile* profile() { return profile_; }
 
   // Extension id of extension receiving keyboard events.
   void SetKeyboardListenerExtensionId(const std::string& id,
                                       content::BrowserContext* context);
   const std::string& keyboard_listener_extension_id() {
     return keyboard_listener_extension_id_;
   }
 
@@ skipping 130 matching lines @@
   scoped_ptr<AccessibilityHighlightManager> accessibility_highlight_manager_;
 
   base::WeakPtrFactory<AccessibilityManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AccessibilityManager);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_ACCESSIBILITY_MANAGER_H_