Put ViEFrameProviderBase::DeliverFrame back in the critical section in ViECapturer::DeliverI420Frame

The CL that moved it out of the critical section is here: https://webrtc-codereview.appspot.com/43669004/

BUG=1128
R=tommi@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/45679005

Cr-Commit-Position: refs/heads/master@{#8724}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8724 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed