Add new task flag when starting chooser activity in bug report.

This flag is required whenever starting an activity from a
non-activity context.

Change-Id: Ia77e6e7801d712a20d407bc2ac92e543bc287010
Fixes: 62016780
Test: Click on generated bug report notification

packages/Shell/src/com/android/shell/BugreportProgressService.java

@@ -981,6 +981,8 @@ public class BugreportProgressService extends Service {
         // Since we may be launched behind lockscreen, make sure that ChooserActivity doesn't finish
         // itself in onStop.
         chooserIntent.putExtra(ChooserActivity.EXTRA_PRIVATE_RETAIN_IN_ON_STOP, true);
+        // Starting the activity from a service.
+        chooserIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
         context.startActivity(chooserIntent);
     }