Move ShowState-related code from PlatformWindowMus to NativeWidgetMus

ui/views/mus/window_tree_host_mus.cc

Index: ui/views/mus/window_tree_host_mus.cc
diff --git a/ui/views/mus/window_tree_host_mus.cc b/ui/views/mus/window_tree_host_mus.cc
index c388453e23044cf4990921f9d9f011864cd4dd38..e360eb05b46ba0ed6769758e0e49a248ecd6b3d9 100644
--- a/ui/views/mus/window_tree_host_mus.cc
+++ b/ui/views/mus/window_tree_host_mus.cc
@@ -20,8 +20,7 @@ namespace views {
 WindowTreeHostMus::WindowTreeHostMus(shell::Connector* connector,
                                      NativeWidgetMus* native_widget,
                                      mus::Window* window)
-    : native_widget_(native_widget),
-      show_state_(ui::PLATFORM_WINDOW_STATE_UNKNOWN) {
+    : native_widget_(native_widget) {
   SetPlatformWindow(
       base::WrapUnique(new PlatformWindowMus(this, connector, window)));
   // The location of events is already transformed, and there is no way to
@@ -59,10 +58,6 @@ void WindowTreeHostMus::OnClosed() {
     native_widget_->OnPlatformWindowClosed();
 }
 
-void WindowTreeHostMus::OnWindowStateChanged(ui::PlatformWindowState state) {
-  show_state_ = state;
-}
-
 void WindowTreeHostMus::OnActivationChanged(bool active) {
   if (active)
     GetInputMethod()->OnFocus();