Cherry pick from webrtc updates of video capture stuff. Not yet tested so to be done later in integration task of video feature.

git-svn-id: http://csipsimple.googlecode.com/svn/trunk/CSipSimple@2155 9f815046-5998-e9c0-b7e2-ac03a23edfa4
Fixes issue 2190.
Big thanks to Misi for the investigation and the fix of the problem !

git-svn-id: http://csipsimple.googlecode.com/svn/trunk/CSipSimple@2156 9f815046-5998-e9c0-b7e2-ac03a23edfa4