Bug 1513855 ensure we notify quit application when running silent r=kmag

Running with -silent does not result in the quit application granted notification.
Without that notification, we have a deadlock in EnvironmentAddonBuilder where it blocks
beforeShutdown waiting on the XPIDatabase to load.

Differential Revision: https://phabricator.services.mozilla.com/D41877

--HG--
extra : moz-landing-system : lando

browser/components/BrowserContentHandler.jsm

@@ -1034,6 +1034,19 @@ nsDefaultCommandLineHandler.prototype = {
       if (win) {
         win.close();
       }
+      // If this is a silent run where we do not open any window, we must
+      // notify shutdown so that the quit-application-granted notification
+      // will happen.  This is required in the AddonManager to properly
+      // handle shutdown blockers for Telemetry and XPIDatabase.
+      // Some command handlers open a window asynchronously, so lets give
+      // that time and then verify that a window was not opened before
+      // quiting.
+      Services.tm.idleDispatchToMainThread(() => {
+        win = Services.wm.getMostRecentWindow(null);
+        if (!win) {
+          Services.startup.quit(Services.startup.eForceQuit);
+        }
+      }, 1);
     }
   },