Factor out more MSE test setup to the helper function.  No bug.  DONTBUILD
Bug 1062657 - Tweak SourceBuffer::AppendData overlap algorithm and switch internal SourceBuffer timestamp handling from double/seconds to int64_t/microseconds.  r=karlt
Bug 1065218 - Convert MediaSourceReader timestamp handling to int64_t/microseconds.  r=karlt
Bug 1065219 - Move track format rejection from switch to init time.  r=cajbir