Revert r157378 as it caused WebRTC to dereference null pointers when restarting a call.

      I've kept my unit test changes intact but disabled until I get a proper fix.

BUG=147499,150805
TBR=henrika

Review URL: https://codereview.chromium.org/10946040

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@157626 0039d316-1c4b-4281-b951-d872f2087c98