Keep initial zoom overview for non-standard load.

In case of non-standard load such as reload, currently the ZoomManager's
onFirstLayout will not be triggered, hence initial zoom overview will not
be set.

This change provides a fix to set initial zoom overview in case of
non-standard load for the new picture after first layout.

issue: 4975315
Change-Id: If2ba3e472f2bb7b6fc4c52024d18a66dc1e41a23