Bug 881512 - Temp fix: don't call mParentDecoder functions while SBD runs off decode thread.  Revert when SBD runs on state machine's task queue.
Bug 881512 - Don't pretend the entire resource is always completely cached.
Bug 881512 - Use the base video and audio queues.  Currently works by shifting media data from the sub-reader queues on each decode call.  Future work could allow the sub-readers to use the base queues directly.