Update the layout mode first when exiting tablet mode

ash/common/shell_observer.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_COMMON_SHELL_OBSERVER_H_
 #define ASH_COMMON_SHELL_OBSERVER_H_
 
 #include "ash/ash_export.h"
 #include "ash/common/login_status.h"
 
@@ skipping 42 matching lines @@
   // get re-arranged).
   virtual void OnOverviewModeStarting() {}
 
   // Called after overview mode has ended.
   virtual void OnOverviewModeEnded() {}
 
   // Called when the always maximize mode has started. Windows might still
   // animate though.
   virtual void OnMaximizeModeStarted() {}
 
-  // Called when the always maximize mode has ended. Windows may still be
+  // Called when the maximize mode is about to end.
+  virtual void OnMaximizeModeEnding() {}

[Mr4D (OOO till 08-26), 2017/02/21 16:17:18]

Sooner or later we should rename the "..MaximizeMode.." into something like
"..TabletMode.." since that is what it is. But that is something for another
refactor patch.

+
+  // Called when the maximize mode has ended. Windows may still be
   // animating but have been restored.
   virtual void OnMaximizeModeEnded() {}
 
   // Called when keyboard is activated/deactivated.
   virtual void OnVirtualKeyboardStateChanged(bool activated) {}
 
   // Called at the end of Shell::Init.
   virtual void OnShellInitialized() {}
 
  protected:
   virtual ~ShellObserver() {}
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SHELL_OBSERVER_H_