Add startup_notify field to apps.proto

This patch adds a bool field startup_notify to apps.proto,
corresponding to the StartupNotify field from the Desktop Entry Spec.

https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-1.1.html#recognized-keys

Bug: 821662
Change-Id: Ibebdca22d8c52a175113ffcf4d7e169512926b4b
Reviewed-on: https://chromium-review.googlesource.com/1021202
Commit-Ready: Timothy Loh <timloh@chromium.org>
Tested-by: Timothy Loh <timloh@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
diff --git a/dbus/vm_applications/apps.proto b/dbus/vm_applications/apps.proto
index 76c2390..4d17a9d 100644
--- a/dbus/vm_applications/apps.proto
+++ b/dbus/vm_applications/apps.proto
@@ -29,6 +29,7 @@
   repeated string mime_types = 4;
   bool no_display = 5;
   string startup_wm_class = 6;
+  bool startup_notify = 7;
 }
 
 message ApplicationList {