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At present ChildProcessSecurityPolicyImpl::SecurityState stores only a
single BrowsingInstanceID (the lowest) even though its associated
process may contain multiple BrowsingInstances. This may lead
CanAccessDataForOrigin to consider the wrong BrowsingInstance when
performing its checks for opt-in isolated origins.

This CL converts SecurityState to track an ordered set of all the
BrowsingInstanceIDs so that they can all be checked.
CanAccessDataForOrigin is modified to return 'true' if *any*
BrowsingInstance in the set would allow the access, otherwise it returns
'false', and logs the failure reasons for each of the BrowsingInstances.

This CL also includes delayed cleanup of BrowsingInstance state from
ChildProcessSecurityPolicy when BrowsingInstances are deleted. This
avoids memory leaks but may pose a small risk of renderer kills. We will
monitor the CanAccessDataForOrigin crash keys to see if such cases
occur in practice.

This is a reland of
https://chromium-review.googlesource.com/c/chromium/src/+/2446370.
The issues that led to https://crbug.com/1141877 are fixed in
https://chromium-review.googlesource.com/c/chromium/src/+/2523732
and include a test that becomes meaningful once this CL lands.

Bug: 1135539, 1141721
Change-Id: I33da01254aaf9e0bb29635cf6b68d85f4823684f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2522904
Commit-Queue: James MacLean <wjmaclean@chromium.org>
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Reviewed-by: Charlie Reis <creis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826024}