Fix a bug where no URL means refresh never ends

This patch does two things:
- If there is no URL to download new data from, then the
Refresh button is not shown.
- Even if for some reason refresh starts for a client for
which there is no URL, loading correctly finishes.

Bug: 9388602
Change-Id: I3fd9214da50faa4b59d0bd3e775293dd34f07547