Account for the OS returning an empty certificate chain.

net/cert/x509_certificate_unittest.cc

Index: net/cert/x509_certificate_unittest.cc
diff --git a/net/cert/x509_certificate_unittest.cc b/net/cert/x509_certificate_unittest.cc
index 74ded45bd1ba617829c2b0f93edbb6788c6e4bef..ae8590c584a482c4f46142dd0b23fcbfc364a25c 100644
--- a/net/cert/x509_certificate_unittest.cc
+++ b/net/cert/x509_certificate_unittest.cc
@@ -1158,12 +1158,23 @@ const struct PublicKeyInfoTestData {
   size_t expected_bits;
   X509Certificate::PublicKeyType expected_type;
 } kPublicKeyInfoTestData[] = {
-  { "768-rsa-ee-by-768-rsa-intermediate.pem", 768,
-    X509Certificate::kPublicKeyTypeRSA },
-  { "1024-rsa-ee-by-768-rsa-intermediate.pem", 1024,
-    X509Certificate::kPublicKeyTypeRSA },
-  { "prime256v1-ecdsa-ee-by-1024-rsa-intermediate.pem", 256,
-    X509Certificate::kPublicKeyTypeECDSA },
+    {"768-rsa-ee-by-768-rsa-intermediate.pem",
+     768,
+     X509Certificate::kPublicKeyTypeRSA},
+    {"1024-rsa-ee-by-768-rsa-intermediate.pem",
+     1024,
+     X509Certificate::kPublicKeyTypeRSA},
+    {"prime256v1-ecdsa-ee-by-1024-rsa-intermediate.pem",
+     256,
+     X509Certificate::kPublicKeyTypeECDSA},
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+    // OS X has an key length limit of 4096 bits. This should manifest as an
+    // unknown key. If a future version of OS X changes this, large_key.pem may
+    // need to be renegerated with a larger key. See https://crbug.com/472291.
+    {"large_key.pem", 0, X509Certificate::kPublicKeyTypeUnknown},
+#else
+    {"large_key.pem", 4104, X509Certificate::kPublicKeyTypeRSA},
+#endif
 };
 
 class X509CertificatePublicKeyInfoTest