Extensions: Hide OneGoogleBar requests from extensions.

LocalNtpSource serves resources for the local New Tab page. It makes browser
requests to fetch one google bar data over the network. This is then served to
the local NTP renderer.

Currently, extensions can intercept these requests using the Web Request API.
However, this is not desired as the NTP is a semi-privileged process. Hide these
requests from extensions.

BUG=797461

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_mojo
Change-Id: Ic8bb3268ba37ec859237f6805bba9a96cae6d464
Reviewed-on: https://chromium-review.googlesource.com/1026996
Commit-Queue: Karan Bhatia <karandeepb@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#554631}
10 files changed