Fix improper transition from gallery to camera

Camera app has been wrongly falling back from the gallery to camera
activity. It happens when a user deletes images and only one image left.
This patch fixes it so that the app can stay at the gallery.

Bug: 113361301
Test: 1) Capture a few photos.
2) Move to film view by dragging screen from right to left.
3) Try to delete photos except one by dragging from bottom to up.

Change-Id: I72c0c678df76386e891a9a1b3dfcaa7e452afd27