[WIP] ash/extensions: Add experimental extension support for window-management in ash.

ash/test/test_shell_delegate.h

Index: ash/test/test_shell_delegate.h
diff --git a/ash/test/test_shell_delegate.h b/ash/test/test_shell_delegate.h
index 88b861637e97747580cf3eb04c1ba5ac16daaa27..33561c05f10d648dcbc266a2e64dbed7d2399e3a 100644
--- a/ash/test/test_shell_delegate.h
+++ b/ash/test/test_shell_delegate.h
@@ -42,6 +42,8 @@ class TestShellDelegate : public ShellDelegate {
   virtual SystemTrayDelegate* CreateSystemTrayDelegate(SystemTray* t) OVERRIDE;
   virtual UserWallpaperDelegate* CreateUserWallpaperDelegate() OVERRIDE;
   virtual aura::client::UserActionClient* CreateUserActionClient() OVERRIDE;
+  virtual ash::WindowManagerExtensionDelegate*
+      CreateWindowManagerDelegate() OVERRIDE { return NULL; }
   virtual void OpenFeedbackPage() OVERRIDE;
   virtual void RecordUserMetricsAction(UserMetricsAction action) OVERRIDE;