Chrome Settings Hardening

Introduces various settings enforcement levels when untrusted settings are detected.

Uses value-parametrized tests to test all enforcement levels:
https://code.google.com/p/googletest/wiki/AdvancedGuide#How_to_Write_Value-Parameterized_Tests

Review URL: https://codereview.chromium.org/122653005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242967 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242967