Update the layout mode first when exiting tablet mode

components/exo/keyboard.cc

 // Copyright 2015 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 "components/exo/keyboard.h"
 
 #include "components/exo/keyboard_delegate.h"
 #include "components/exo/keyboard_device_configuration_delegate.h"
 #include "components/exo/shell_surface.h"
 #include "components/exo/surface.h"
@@ skipping 203 matching lines @@
   }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // WMHelper::MaximizeModeObserver overrides:
 
 void Keyboard::OnMaximizeModeStarted() {
   OnKeyboardDeviceConfigurationChanged();
 }
 
+void Keyboard::OnMaximizeModeEnding() {}
+
 void Keyboard::OnMaximizeModeEnded() {
   OnKeyboardDeviceConfigurationChanged();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // Keyboard, private:
 
 Surface* Keyboard::GetEffectiveFocus(aura::Window* window) const {
   // Use window surface as effective focus.
   Surface* focus = Surface::AsSurface(window);
   if (!focus) {
     // Fallback to main surface.
     aura::Window* top_level_window = window->GetToplevelWindow();
     if (top_level_window)
       focus = ShellSurface::GetMainSurface(top_level_window);
   }
 
   return focus && delegate_->CanAcceptKeyboardEventsForSurface(focus) ? focus
                                                                       : nullptr;
 }
 
 }  // namespace exo