Add SETTINGS_ENABLE_CONNECT_PROTOCOL.

Add SETTINGS_ENABLE_CONNECT_PROTOCOL to enum SpdySettingsIds and
add SpdySession::support_websocket_ with accessor and unittests.

This CL lands internal change 181778518.

Bug: 801564, 488484
Change-Id: I35b9361234672b1dc08c5c0a9cf2b780575fe344
Reviewed-on: https://chromium-review.googlesource.com/864745
Commit-Queue: Bence Béky <bnc@chromium.org>
Reviewed-by: Helen Li <xunjieli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531561}
6 files changed