measure clean versus unclean exits

Summary:
This adds another field to the exit data to record whether we had a clean exit where the app was closed as it should.

Note that doing a reload inside Flipper will be recorded as an unclean exit.

Reviewed By: passy

Differential Revision: D20915481

fbshipit-source-id: 240192d7a69bf620bfaa316e3e5cb0f45d6a34cc

desktop/static/main.ts

@@ -310,7 +310,7 @@ function tryCreateWindow() {
     });
     win.once('ready-to-show', () => win.show());
     win.once('close', () => {
-      win.webContents.send('trackUsage');
+      win.webContents.send('trackUsage', 'exit');
       if (process.env.NODE_ENV === 'development') {
         // Removes as a default protocol for debug builds. Because even when the
         // production application is installed, and one tries to deeplink through