GitLab

Adds tests to ensure that about:policy loads properly and that policies
are parsed properly out of NSUserDefaults.

Adds EG2 helpers to retrieve policy settings from the current platform
policy provider.

BUG=1024115,1027249

Change-Id: I9835d106c873efa020293bfff4d59f0feb47abe3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2088532
Commit-Queue: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: Mike Dougherty <michaeldo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#749184}