[NTP] Use lower res thumbnail images for tiles.

Confirmed with the service provider that default image size returned
is 512x512, which is fine to use as-is for tile thumbnails. Options
need to be applied to the same URL to request the image at a higher
resolution when setting as the background image. Using the high res
image for tiles causes a noticeable delay in load time.

Bug: 850314
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: Ic0c758d6326ad34017831bc1340cc292242cfa79
Reviewed-on: https://chromium-review.googlesource.com/1098380
Commit-Queue: Ramya Nagarajan <ramyan@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#566992}
5 files changed