Disables ctrl-shift-q on login screen

ash/accelerators/accelerator_table.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/accelerators/accelerator_table.h"
 
 #include "base/basictypes.h"
 
 namespace ash {
 
@@ skipping 101 matching lines @@
   { ui::ET_TRANSLATED_KEY_PRESS, ui::VKEY_F4, true, true, false,
     CYCLE_MONITOR },
 #endif
 };
 
 const size_t kAcceleratorDataLength = arraysize(kAcceleratorData);
 
 const AcceleratorAction kActionsAllowedAtLoginScreen[] = {
   BRIGHTNESS_DOWN,
   BRIGHTNESS_UP,
-  EXIT,
   NEXT_IME,
   PREVIOUS_IME,
   SWITCH_IME,  // Switch to another IME depending on the accelerator.
   TAKE_SCREENSHOT,
   TAKE_PARTIAL_SCREENSHOT,
   VOLUME_DOWN,
   VOLUME_MUTE,
   VOLUME_UP,
   ROTATE_WINDOWS,
 #if !defined(NDEBUG)
   PRINT_LAYER_HIERARCHY,
   PRINT_WINDOW_HIERARCHY,
   ROTATE_SCREEN,
 #endif
 };
 
 const size_t kActionsAllowedAtLoginScreenLength =
     arraysize(kActionsAllowedAtLoginScreen);
 
 }  // namespace ash