Revert 241657 "Implement chromium's TLS."

Caused intermittent browser process crashes on Linux Debug configurations.
See Issue 329747 for details.

BUG=329747,264406

> 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

TBR=michaelbai@chromium.org

Review URL: https://codereview.chromium.org/121393002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242549 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242549