Enable swap primary accelerator only when possible

ash/accelerators/accelerator_controller.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_controller.h"
 
 #include <algorithm>
 #include <cmath>
 #include <string>
 #include <utility>
@@ skipping 1032 matching lines @@
     case SWITCH_TO_PREVIOUS_USER:
     case SWITCH_TO_NEXT_USER:
       return CanHandleCycleUser();
     case TOGGLE_CAPS_LOCK:
       return CanHandleToggleCapsLock(accelerator, previous_accelerator);
     case TOGGLE_TOUCH_VIEW_TESTING:
       return CanHandleToggleTouchViewTesting();
     case TOUCH_HUD_CLEAR:
     case TOUCH_HUD_MODE_CHANGE:
       return CanHandleTouchHud();
+    case SWAP_PRIMARY_DISPLAY:
+      return gfx::Screen::GetScreen()->GetNumDisplays() > 1;
 #endif
-
     case CYCLE_BACKWARD_MRU:
     case CYCLE_FORWARD_MRU:
     case EXIT:
     case FOCUS_NEXT_PANE:
     case FOCUS_PREVIOUS_PANE:
     case FOCUS_SHELF:
     case LAUNCH_APP_0:
     case LAUNCH_APP_1:
     case LAUNCH_APP_2:
     case LAUNCH_APP_3:
@@ skipping 27 matching lines @@
     case DISABLE_GPU_WATCHDOG:
     case KEYBOARD_BRIGHTNESS_DOWN:
     case KEYBOARD_BRIGHTNESS_UP:
     case LOCK_PRESSED:
     case LOCK_RELEASED:
     case OPEN_CROSH:
     case OPEN_FILE_MANAGER:
     case OPEN_GET_HELP:
     case POWER_PRESSED:
     case POWER_RELEASED:
-    case SWAP_PRIMARY_DISPLAY:
     case TOGGLE_MIRROR_MODE:
     case TOGGLE_SPOKEN_FEEDBACK:
     case TOGGLE_WIFI:
     case TOUCH_HUD_PROJECTION_TOGGLE:
     case VOLUME_DOWN:
     case VOLUME_MUTE:
     case VOLUME_UP:
 #else
     case DUMMY_FOR_RESERVED:
 #endif
@@ skipping 317 matching lines @@
 }
 
 void AcceleratorController::SetKeyboardBrightnessControlDelegate(
     scoped_ptr<KeyboardBrightnessControlDelegate>
     keyboard_brightness_control_delegate) {
   keyboard_brightness_control_delegate_ =
       std::move(keyboard_brightness_control_delegate);
 }
 
 }  // namespace ash