[WebSocket] Add Cache-Control to the request header.

In order to suppress cache on servers, added LOAD_BYPASS_CACHE to
the load flags.
Additionally, added some messages on opening handshake failure.

BUG=339373

Review URL: https://codereview.chromium.org/152483003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248971 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248971