ash: Remove ash::Shelf in favor of ash::WmShelf

ash/shell.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_SHELL_H_
 #define ASH_SHELL_H_
 
 #include <memory>
 #include <utility>
 #include <vector>
@@ skipping 94 matching lines @@
 class ResizeShadowController;
 class ResolutionNotificationController;
 class RootWindowController;
 class ScopedOverviewAnimationSettingsFactoryAura;
 class ScreenAsh;
 class ScreenOrientationController;
 class ScreenshotController;
 class ScreenPinningController;
 class ScreenPositionController;
 class SessionStateDelegate;
-class Shelf;
 class ShellDelegate;
 struct ShellInitParams;
 class SlowAnimationEventFilter;
 class StatusAreaWidget;
 class StickyKeysController;
 class StylusMetricsRecorder;
 class SystemGestureEventFilter;
 class SystemModalContainerEventFilter;
 class SystemTray;
 class ToplevelWindowEventHandler;
@@ skipping 468 matching lines @@
   base::SequencedWorkerPool* blocking_pool_;
 
   bool in_mus_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(Shell);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELL_H_