Add STATE_MAXIMIZED to the list of possible window states in MapWindow().

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc

Index: ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
index ee1e3849aa050c6e6ab168217c66b7dcd580267c..4cae6165226ebb9f6c95b3b38e23a954e346a9fc 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc
@@ -1551,7 +1551,8 @@ std::list<XID>& DesktopWindowTreeHostX11::open_windows() {
 void DesktopWindowTreeHostX11::MapWindow(ui::WindowShowState show_state) {
   if (show_state != ui::SHOW_STATE_DEFAULT &&
       show_state != ui::SHOW_STATE_NORMAL &&
-      show_state != ui::SHOW_STATE_INACTIVE) {
+      show_state != ui::SHOW_STATE_INACTIVE &&
+      show_state != ui::SHOW_STATE_MAXIMIZED) {
     // It will behave like SHOW_STATE_NORMAL.
     NOTIMPLEMENTED();
   }