Add X509CertificateBytes which uses CRYPTO_BUFFER instead of macOS-native certificate types.

build/config/BUILD.gn

Index: build/config/BUILD.gn
diff --git a/build/config/BUILD.gn b/build/config/BUILD.gn
index e774b20a1fd74d8301bafae8c179caf4f89cf312..8b37ea88e53b82736c028459a946142b53a0c5eb 100644
--- a/build/config/BUILD.gn
+++ b/build/config/BUILD.gn
@@ -72,6 +72,9 @@ config("feature_flags") {
   if (use_glib) {
     defines += [ "USE_GLIB=1" ]
   }
+  if (use_byte_certs) {

[eroman, 2017/03/29 23:06:54]

Not sure if the OWNERS will be open to this, given the warning comments above. I
guess the alternative could be to express USE_BYTE_CERTS in terms of
platform-defines.

[mattm, 2017/03/30 04:38:09]

Switched to a buildflag defined in net/BUILD.gn.

+    defines += [ "USE_BYTE_CERTS=1" ]
+  }
   if (use_openssl_certs) {
     defines += [ "USE_OPENSSL_CERTS=1" ]
   }