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

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

R=rch@chromium.org, wtc@chromium.org

[Ryan Hamilton, 2013-10-08 22:59:37]

lgtm

[wtc, 2013-10-09 23:01:28]

Patch set 2 LGTM.

https://codereview.chromium.org/26471007/diff/4001/net/quic/crypto/crypto_uti...
File net/quic/crypto/crypto_utils.h (right):

https://codereview.chromium.org/26471007/diff/4001/net/quic/crypto/crypto_uti...
net/quic/crypto/crypto_utils.h:58: static bool DeriveKeys(base::StringPiece
premaster_secret,

Nit: document the return value.