[NTP] Allow testing of interactive Doodles

The Doodle team tests interactive doodles by running a local
demo and supplying the --google-base-url to Chrome. Substitute
'https://www.google.com' in the interactive doodle url with
the given url. Add the base url to the NTP's CSP child-src
directive.

Bug: 583290
Change-Id: Ib28bd6dd513ddcde073d516876c480e322367ad9
Reviewed-on: https://chromium-review.googlesource.com/c/1373886
Commit-Queue: Kyle Milka <kmilka@chromium.org>
Reviewed-by: Ramya Nagarajan <ramyan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616764}
2 files changed