Crop PDF Thumbnails before sending them from Provider

Essentially, if you were to get a PDF Thumbnail for a landscape-oriented
ImageView (more horizontal than vertical), it would just squish the
whole PDF page down. This crops it so it looks nice in landscape and
portrait.

Bug: 63928143
Test: In place
Change-Id: Iaefabba1a96dcee5297bf6639aba8098c9137782