Implement chromium's TLS.

Using one system TLS to implement multiple chrome's TLS slots.

BUG=264406

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=241144

Review URL: https://codereview.chromium.org/60743004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241657 0039d316-1c4b-4281-b951-d872f2087c98
5 files changed