Bug 1049317 - Simplify SourceBufferResource::ReadFromCache.  r=cajbir
Bug 1049323 - Tidy up SourceBufferResource logging.  r=cajbir
Bug 1049317 - SBR::ReadFromCache forgot to reset offset.  r=cajbir
Bug 1049323 - Tidy up MSE logging.  r=cajbir
Bug 1049326 - Fix unit conversion of duration and other minor MSE cleanups.  r=cajbir
Bug 1049327 - Assert that public MSE API is only called from the main thread. r=cajbir
Bug 1049326 - Partially implement EndOfStream.  r=cajbir
Bug 1049321 - Move SubBufferDecoder to a new file.  r=cajbir
Bug 1049318 - Make SourceBuffer eviction less aggressive.  r=cajbir
Bug 1050083 - Changes to WebM buffered range handling.  r=cajbir

Include the frame duration in the range end.  Also handle (ignore) invalid
negative timestamps when parsing.  Include cluster offset in time/data
offset record.  Cluster offset will be used when calculating discard/resync
points in MSE.
Bug 1050099 - Avoid calling deprecated FindStartTime and instead use buffer's decoded ranges in switching logic.  r=cajbir