net: disable ChaCha20 based cipher suites.

We're not ready for this in M32:
  * The Windows compiler doesn't support vector code so we're using generic
    code there.
  * We don't have promotion for AES-GCM ciphersuites when AES-NI is supported.

This change is designed to be reverted on trunk once M32 has branched.

BUG=315791

Review URL: https://codereview.chromium.org/60353005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233470 0039d316-1c4b-4281-b951-d872f2087c98

net/socket/nss_ssl_util.cc

@@ -70,6 +70,11 @@ class NSSSSLInitSingleton {
           enabled = false;
         }
 
+        // We also disable ChaCha20 based cipher suites for now because we
+        // aren't quite ready to use them in M32.
+        if (info.symCipher == ssl_calg_chacha20)
+          enabled = false;
+
         if (ssl_ciphers[i] == TLS_DHE_DSS_WITH_AES_128_CBC_SHA) {
           // Enabled to allow servers with only a DSA certificate to function.
           enabled = true;