Remove the old SocketStream-based WebSocket implementation from
content/.
Large parts of the implementation still exist in net/. They will be
removed in a subsequent CL.
There are also a few traces in chrome/, and some interfaces in Blink
that cannot be removed until this CL is submitted.
BUG=423201
TEST=layout tests, browser_tests
Review URL: https://codereview.chromium.org/655253006
Cr-Commit-Position: refs/heads/master@{#301075}
8e60ab5d14