Load correct thumbnail size when switching to grid from list (and visa versa).

This is a quickie change where we clear the cache, but I think there could be
a better behavior where we don't clear the cache, show low res (instantly)
then load higher resolution ontop of the low res.

Bug: 26763078
Change-Id: If9883d507984b555e790a06692390d4fa3334c28
1 file changed