Advertise the permessage-deflate extension and enable it when requested by the server.

Also validation and parsing of the permessage-deflate extension parameters, and unit tests.

BUG=280910
TEST=net_unittests --gtest_filter=WebSocket*

Review URL: https://codereview.chromium.org/143913003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247545 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247545