Possible resize flickering on config change

It is possible that while a config change is going on, the
view hiererchy got created but not layouted. In that case
the reported size of the main window would be 0,0. In this
event we need to use the cached window sizes from the past
render.

Bug: 24595899
Change-Id: Ia41f7ae0999e4f2bda364506029bcbdfd7d3f4b4