Add ShellDelegate, MediaDelegate and KeyboardUI stubs to mus ash

ash/common/wm_shell.cc

Index: ash/common/wm_shell.cc
diff --git a/ash/common/wm_shell.cc b/ash/common/wm_shell.cc
index 45a8983c1c452ca1dd4efd8f3d4289b4f01ac7f0..a1b8d99259d16ce0077b11309bc44b47b0ee7977 100644
--- a/ash/common/wm_shell.cc
+++ b/ash/common/wm_shell.cc
@@ -4,6 +4,8 @@
 
 #include "ash/common/wm_shell.h"
 
+#include <utility>
+
 #include "ash/common/focus_cycler.h"
 #include "ash/common/keyboard/keyboard_ui.h"
 #include "ash/common/shell_delegate.h"
@@ -66,8 +68,8 @@ void WmShell::RemoveShellObserver(ShellObserver* observer) {
   shell_observers_.RemoveObserver(observer);
 }
 
-WmShell::WmShell(ShellDelegate* delegate)
-    : delegate_(delegate),
+WmShell::WmShell(std::unique_ptr<ShellDelegate> shell_delegate)
+    : delegate_(std::move(shell_delegate)),
       focus_cycler_(new FocusCycler),
       system_tray_notifier_(new SystemTrayNotifier),
       window_selector_controller_(new WindowSelectorController) {