Bug 837539 - Fix crashes due to premature deinitialization. r=rjesup,bgirard a=lsblakk
Bug 843214. Make SourceMediaStream::AddTrack/AppendToTrack/HaveEnoughBuffered/DispatchWhenNotEnoughBuffered/EndTrack smoothly handle cases where track does not exist. r=jesup a=lsblakk
Backout of 64df2203966e due to regression. [r=me] [a=bbajaj]