Reason for revert: API changes broke downstream. Original issue's description: > Deprecate VCMPacketizationCallback::SendData and use EncodedImageCallback instead. > EncodedImageCallback is used by all encoder implementations and seems to be what we should try to use in the transport. > EncodedImageCallback can of course be cleaned up in the future. > > This moves creation of RTPVideoHeader from the GenericEncoder to the PayLoadRouter. > > BUG=webrtc::5687 > > Committed: https://crrev.com/f5d55aaecdc39e9cc66eb6e87614f04afe28f6eb > Cr-Commit-Position: refs/heads/master@{#12436} TBR=stefan@webrtc.org,pbos@webrtc.org,perkj@webrtc.org # Skipping CQ checks because original CL landed less than 1 days ago. NOPRESUBMIT=true NOTREECHECKS=true NOTRY=true BUG=webrtc::5687 Review URL: https://codereview.webrtc.org/1903193002 Cr-Commit-Position: refs/heads/master@{#12441}