Bug 1067414 - Convert CubebUtils from a class of statics to a namespace.
Bug 1067414 - Add a comment about thread-safety of unlocked sPreferredSampleRate reads.

Also, fix return type of MaxNumberOfChannels and PreferredSampleRate.
Bug 1065250 - Factor part of SourceBuffer::AppendData into new PrepareAppend function.  r=karlt
Bug 1065250 - Factor some of SourceBuffer::AppendData into TrackBuffer::Append.  Move ContainerParser to a new file.  r=karlt

--HG--
rename : content/media/mediasource/SourceBuffer.cpp => content/media/mediasource/ContainerParser.cpp
Bug 1065250 - Tidy up unneeded includes after several refactorings.  r=karlt