Media search dialog: Only try to abort request if possible

Sometimes we have to load images in a way that we can't abort.
In that case, don't bother trying to abort, it just creates annoying console
messages.

Bug: 59604
Change-Id: Idb675f57284d9ffa1fe69c87806009a31711dabe
Merge "Media search dialog: Only try to abort request if possible"