Land Recent QUIC changes.

Remove unused IsWriteBlocked method from QuicConnectionHelperInterface.

Merge internal change: 53803217

Add missing QUIC_VERSION_Q011 case in QuicVersionToString.

Merge internal change: 53749976

QUIC: don't ignore SetKey and SetNoncePrefix return values.

This change causes failures to set the AES-GCM key and nonce to bubble
up and kill the connection. I don't think that we've had any failures,
but you never know and it would be bad to, say, start transmitting
plaintext or something because we didn't notice that we failed to set
a key.

(The OpenSSL AEAD API doesn't actually let that happen: it zeros the
output buffer on any failure, but things might change in the future.)

(This is a follow up from a previous CL which altered our AES-128-GCM
implementation.)

Merge internal change: 53742674

Reduce the length of the QUIC null encryption auth hash from 16 bytes to
12 bytes to match the length of the AES auth hash.

Merge internal change: 53693995

R=rch@chromium.org

Review URL: https://codereview.chromium.org/26739002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228145 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228145