Added a BitBufferWriter subclass that contains methods for writing bit and byte-sized data, along with exponential golomb encoded data.

This pattern (read-only base, writable subclass) was picked to maintain a *Buffer option that doesn't copy the source bits when parsing. ByteBuffer and Buffer both copy. I'm open to discussion on what the type relationship would be, though :)

Tests have been added to ensure the symmetric nature of read/write operations.

BUG=
R=bcornell@google.com, pthatcher@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/45259005

Cr-Commit-Position: refs/heads/master@{#9107}
3 files changed