GitLab

This tracks per host data savings for offline previews as well as
cleaning up the code somewhat.

Bug: 794642
Change-Id: I2660beeee2c6ef8f7939eff4861b78203dab63d6
Reviewed-on: https://chromium-review.googlesource.com/825362
Commit-Queue: Ryan Sturm <ryansturm@chromium.org>
Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524194}