Moves MruWindowTracker into common

ash/aura/wm_shell_aura.cc

 // Copyright 2016 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/aura/wm_shell_aura.h"
 
 #include "ash/aura/wm_window_aura.h"
+#include "ash/common/wm/mru_window_tracker.h"
 #include "ash/common/wm_activation_observer.h"
 #include "ash/common/wm_display_observer.h"
 #include "ash/common/wm_overview_mode_observer.h"
 #include "ash/display/window_tree_host_manager.h"
 #include "ash/session/session_state_delegate.h"
 #include "ash/shell.h"
 #include "ash/shell_delegate.h"
 #include "ash/wm/drag_window_resizer.h"
-#include "ash/wm/mru_window_tracker.h"
 #include "ash/wm/overview/window_selector_controller.h"
 #include "ash/wm/window_util.h"
 #include "base/memory/ptr_util.h"
 #include "ui/aura/client/focus_client.h"
 #include "ui/wm/public/activation_client.h"
 
 namespace ash {
 
 WmShellAura::WmShellAura() {
   WmShell::Set(this);
@@ skipping 172 matching lines @@
   FOR_EACH_OBSERVER(WmDisplayObserver, display_observers_,
                     OnDisplayConfigurationChanged());
 }
 
 void WmShellAura::OnOverviewModeEnded() {
   FOR_EACH_OBSERVER(WmOverviewModeObserver, overview_mode_observers_,
                     OnOverviewModeEnded());
 }
 
 }  // namespace ash