Isn't it better to move the wait in the test? because this method is also used here:
https://github.com/mozilla-b2g/gaia/blob/master/tests/python/gaia-ui-tests/gaiatest/apps/camera/app.py#L134
and here:
https://github.com/mozilla-b2g/gaia/blob/master/tests/python/gaia-ui-tests/gaiatest/tests/functional/camera/test_camera_capture_photo.py#L29