This flag is passed to existing VieExternalCodec API (and others) to denote encoders that don't require/expect frames from the normal capture pipeline. This is the simplest way to allow camera->encoder texture support, until textures are supported through the normal camera pipeline and the lifetime issues are all figured out (I hear this is on the backlog, but not there yet).
Ideally, the flag would be on the encoder, but that doesn't work with SimulcastEncoderAdapter, since it doesn't create an encoder right away.
Note that this change only affects WebRtcVideoEngine (not WRVE2), since WRVE2 uses video_send_stream, and my hope is that by the time things have switched to WRVE2, textures will be supported with the normal camera pipeline and the dependency on internal sources can be thrown away.
BUG=
R=pbos@webrtc.org, pthatcher@webrtc.org
Review URL: https://webrtc-codereview.appspot.com/42349004
Cr-Commit-Position: refs/heads/master@{#8769}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8769 4adac7df-926f-26a2-2b94-8c16560cd09d
