Unify window fullscreen and minimizing implementation

ui/views/mus/desktop_window_tree_host_mus.cc

Index: ui/views/mus/desktop_window_tree_host_mus.cc
diff --git a/ui/views/mus/desktop_window_tree_host_mus.cc b/ui/views/mus/desktop_window_tree_host_mus.cc
index 87571a76b30d3abaca869fa53a465775f39b287a..ab67555718382bc10abe9e08f4eafbbfa3229939 100644
--- a/ui/views/mus/desktop_window_tree_host_mus.cc
+++ b/ui/views/mus/desktop_window_tree_host_mus.cc
@@ -177,7 +177,6 @@ DesktopWindowTreeHostMus::DesktopWindowTreeHostMus(
                               mus_properties),
       native_widget_delegate_(native_widget_delegate),
       desktop_native_widget_aura_(desktop_native_widget_aura),
-      fullscreen_restore_state_(ui::SHOW_STATE_DEFAULT),
       close_widget_factory_(this) {
   aura::Env::GetInstance()->AddObserver(this);
   MusClient::Get()->AddObserver(this);
@@ -596,16 +595,9 @@ void DesktopWindowTreeHostMus::SetFullscreen(bool fullscreen) {
   if (IsFullscreen() == fullscreen)
     return;  // Nothing to do.
 
-  // Save window state before entering full screen so that it could restored
-  // when exiting full screen.
-  if (fullscreen) {
-    fullscreen_restore_state_ =
-        window()->GetProperty(aura::client::kShowStateKey);
-  }
-
   window()->SetProperty(
       aura::client::kShowStateKey,
-      fullscreen ? ui::SHOW_STATE_FULLSCREEN : fullscreen_restore_state_);
+      fullscreen ? ui::SHOW_STATE_FULLSCREEN : ui::SHOW_STATE_PREVIOUS);
 }
 
 bool DesktopWindowTreeHostMus::IsFullscreen() const {