Remove --ash-enable-tray-dragging flag

ash/ash_switches.h

 // 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.
 
 #ifndef ASH_ASH_SWITCHES_H_
 #define ASH_ASH_SWITCHES_H_
 
 #include "ash/ash_export.h"
 
 #include "build/build_config.h"
@@ skipping 15 matching lines @@
 ASH_EXPORT extern const char kAshDisableTouchExplorationMode[];
 #if defined(OS_CHROMEOS)
 ASH_EXPORT extern const char kAshEnableFullscreenAppList[];
 ASH_EXPORT extern const char kAshEnableMagnifierKeyScroller[];
 #endif
 ASH_EXPORT extern const char kAshEnableMirroredScreen[];
 ASH_EXPORT extern const char kAshEnablePowerButtonQuickLock[];
 ASH_EXPORT extern const char kAshEnableSoftwareMirroring[];
 ASH_EXPORT extern const char kAshEnableSystemSounds[];
 ASH_EXPORT extern const char kAshEnableTouchViewTesting[];
-ASH_EXPORT extern const char kAshEnableTrayDragging[];
 ASH_EXPORT extern const char kAshHideNotificationsForFactory[];
 ASH_EXPORT extern const char kAshHostWindowBounds[];
 ASH_EXPORT extern const char kAshSecondaryDisplayLayout[];
 ASH_EXPORT extern const char kAshTouchHud[];
 ASH_EXPORT extern const char kAshUseFirstDisplayAsInternal[];
 ASH_EXPORT extern const char kAuraLegacyPowerButton[];
 #if defined(OS_WIN)
 ASH_EXPORT extern const char kForceAshToDesktop[];
 #endif
 
 // Returns true if items can be dragged off the shelf to unpin.
 ASH_EXPORT bool UseDragOffShelf();
 
 #if defined(OS_CHROMEOS)
 // Returns true if a notification should appear when a low-power USB charger
 // is connected.
 ASH_EXPORT bool UseUsbChargerNotification();
 #endif
 
 }  // namespace switches
 }  // namespace ash
 
 #endif  // ASH_ASH_SWITCHES_H_