mash: Convert ash::ShellDelegate from aura::Window to WmWindow

ash/common/wm_shell.h

Index: ash/common/wm_shell.h
diff --git a/ash/common/wm_shell.h b/ash/common/wm_shell.h
index 8cd142f4ca3a16a14d9dc0bf8b73893c4bfec3ac..3a34e364139bc846f97dccab6e4602c15ce4d265 100644
--- a/ash/common/wm_shell.h
+++ b/ash/common/wm_shell.h
@@ -70,6 +70,8 @@ class ASH_EXPORT WmShell {
   // Returns true if |window| can be shown for the current user. This is
   // intended to check if the current user matches the user associated with
   // |window|.
+  // TODO(jamescook): Remove this when ShellDelegate is accessible via this
+  // interface.
   virtual bool CanShowWindowForUser(WmWindow* window) = 0;
 
   // See aura::client::CursorClient for details on these.