This makes the ImageBuffer class implement VideoFrameBuffer class and makes
it available in MediaPipeline. To avoid exposing MediaPipeline to a lot of
internal details of WebrtcMediaDataDecoder, ImageBuffer is moved to its
own header file.
We're required to implement a ToI420() method. I've re-used the current
implementation of NativeToI420Buffer, which requires more development in order
to work properly as the Image class only supports RGB readback.
Differential Revision: https://phabricator.services.mozilla.com/D7435
--HG--
extra : rebase_source : 19ec409510f06a9fa7cab15c1f16c9a7bad0b433