Introduce WebSocketDeflateStream.

This CL introduces WebSocketDeflateStream, a WebSocketStream subclass
for permessage-deflate WebSocket extension[1].

Currently the implementation compresses all outgoing data frames: it
should be fixed in the future.

[1] http://tools.ietf.org/html/draft-ietf-hybi-permessage-compression-12

BUG=280910

Review URL: https://codereview.chromium.org/26202002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228129 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228129