GitLab

This CL adds a second SharedResourcesDataSource to
URLDataManagerBackend that is used to host the resources at
chrome-untrusted://resources. This allows chrome-untrusted:// frames to
access shared resources.

Design doc:
https://docs.google.com/document/d/1vM-giNmjhKBLGQHu5wMeMHk8VaqOhDWjVa9pYAKVZKY/edit?usp=sharing

Bug: 1082937
Change-Id: I808f6c3d602c6fead880cf2362963dea6646ad21
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2202673Reviewed-by: Nasko Oskov <nasko@chromium.org>
Reviewed-by: dpapad <dpapad@chromium.org>
Commit-Queue: Tommy Steimel <steimel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#771198}