Splits ToplevelWindowEventHandler into two

ash/wm/aura/wm_globals_aura.h

 // 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.
 
 #ifndef ASH_WM_AURA_WM_GLOBALS_AURA_H_
 #define ASH_WM_AURA_WM_GLOBALS_AURA_H_
 
 #include <set>
 
 #include "ash/ash_export.h"
@@ skipping 43 matching lines @@
   void AddOverviewModeObserver(WmOverviewModeObserver* observer) override;
   void RemoveOverviewModeObserver(WmOverviewModeObserver* observer) override;
 
  private:
   // aura::client::ActivationChangeObserver:
   void OnWindowActivated(ActivationReason reason,
                          aura::Window* gained_active,
                          aura::Window* lost_active) override;
 
   // WindowTreeHostManager::Observer:
+  void OnDisplayConfigurationChanging() override;
   void OnDisplayConfigurationChanged() override;
 
   // ShellObserver:
   void OnOverviewModeEnded() override;
 
   WmLookupAura wm_lookup_;
   bool added_activation_observer_ = false;
   base::ObserverList<WmActivationObserver> activation_observers_;
 
   bool added_display_observer_ = false;
   base::ObserverList<WmDisplayObserver> display_observers_;
 
   base::ObserverList<WmOverviewModeObserver> overview_mode_observers_;
 
   DISALLOW_COPY_AND_ASSIGN(WmGlobalsAura);
 };
 
 }  // namespace wm
 }  // namespace ash
 
 #endif  // ASH_WM_AURA_WM_GLOBALS_AURA_H_