Implement origin specific Permissions Blacklisting.

For Chrome users that have enabled Safe Browsing, when a new permission
request is made, the requesting origin is first checked with Safe
Browsing. If Safe Browsing has blacklisted the origin for the requested
permission, that permission is autoblocked. The origin will only be
autoblocked for blacklisted permissions, any other permissions will
default to the normal prompting for a decision from the user.

Unit tests added to permission_context_base_unittest.cc. Further tests
to follow.

Permissions Blacklisting will also require an update to the UI, which
will also follow.

BUG=561867

Review-Url: https://codereview.chromium.org/2555913002
Cr-Commit-Position: refs/heads/master@{#442501}
3 files changed