Add option to install an ephemeral app to the Windows jump list

apps/ui/native_app_window.h

Index: apps/ui/native_app_window.h
diff --git a/apps/ui/native_app_window.h b/apps/ui/native_app_window.h
index dece2d915907425ed99c2e627273d734828a2c08..2e2811fa5829161f1f0f99325d536de5ef76b202 100644
--- a/apps/ui/native_app_window.h
+++ b/apps/ui/native_app_window.h
@@ -68,6 +68,10 @@ class NativeAppWindow : public ui::BaseWindow,
   // size constraints.
   virtual void UpdateWindowMinMaxSize() = 0;
 
+  // Updates custom entries for the context menu of the app's taskbar/dock/shelf
+  // icon.
+  virtual void UpdateAppMenu() = 0;
+
   virtual ~NativeAppWindow() {}
 };