The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6ab3ac0ff48e8807dceeb198713d829975459452

commit 6ab3ac0ff48e8807dceeb198713d829975459452
Author: Chris Hamilton <chrisha@chromium.org>
Date: Mon Dec 18 17:40:42 2017

Create ThirdPartyBlockingEnabled policy.

This creates a policy for explicitly enabling/disabling third party blocking. Further CLs will integrate this with the blocking and messaging logic.

BUG=789174

Change-Id: I1cdb81cbce2af5ece4e972208f428baab7e53207
Reviewed-on: https://chromium-review.googlesource.com/801894
Commit-Queue: Chris Hamilton <chrisha@chromium.org>
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524736}
[modify] https://crrev.com/6ab3ac0ff48e8807dceeb198713d829975459452/chrome/browser/chrome_content_browser_client.cc
[modify] https://crrev.com/6ab3ac0ff48e8807dceeb198713d829975459452/chrome/browser/policy/configuration_policy_handler_list_factory.cc
[modify] https://crrev.com/6ab3ac0ff48e8807dceeb198713d829975459452/chrome/common/pref_names.cc
[modify] https://crrev.com/6ab3ac0ff48e8807dceeb198713d829975459452/chrome/common/pref_names.h
[modify] https://crrev.com/6ab3ac0ff48e8807dceeb198713d829975459452/chrome/test/data/policy/policy_test_cases.json
[modify] https://crrev.com/6ab3ac0ff48e8807dceeb198713d829975459452/components/policy/resources/policy_templates.json
[modify] https://crrev.com/6ab3ac0ff48e8807dceeb198713d829975459452/tools/metrics/histograms/enums.xml