Make GN build work on Mac again.

net/BUILD.gn

Index: net/BUILD.gn
diff --git a/net/BUILD.gn b/net/BUILD.gn
index cde05e271903225817aa0013b50d4addace0ec87..0dea5e7e07b57d324ae819cd192b6dd7ac8ba208 100644
--- a/net/BUILD.gn
+++ b/net/BUILD.gn
@@ -39,10 +39,6 @@ enable_built_in_dns = !is_ios
 
 enable_ftp_support = !is_ios
 
-# When OpenSSL is used for SSL and crypto on Unix-like systems, use OpenSSL"s
-# certificate definition.
-use_openssl_certs = (is_linux || is_android) && use_openssl
-
 config("net_config") {
   defines = []
   if (posix_avoid_mmap) {
@@ -268,10 +264,7 @@ component("net") {
       "cert/cert_database_nss.cc",
       "cert/nss_cert_database.cc",
       "cert/nss_cert_database.h",
-      "cert/test_root_certs_nss.cc",
       "cert/x509_certificate_nss.cc",
-      "ocsp/nss_ocsp.cc",
-      "ocsp/nss_ocsp.h",
       "third_party/mozilla_security_manager/nsKeygenHandler.cpp",
       "third_party/mozilla_security_manager/nsKeygenHandler.h",
       "third_party/mozilla_security_manager/nsNSSCertificateDB.cpp",
@@ -279,15 +272,31 @@ component("net") {
       "third_party/mozilla_security_manager/nsPKCS12Blob.cpp",
       "third_party/mozilla_security_manager/nsPKCS12Blob.h",
     ]
+
+    if (!is_ios) {
+      # These files are part of the partial implementation of NSS on iOS so
+      # keep them in that case.
+      sources -= [
+        "cert/test_root_certs_nss.cc",
+        "ocsp/nss_ocsp.cc",
+        "ocsp/nss_ocsp.h",
+      ]
+    }
   }
 
-  if (use_openssl) {
+  if (!use_nss_certs) {
     sources -= [
-      "cert/cert_verify_proc_nss.cc",
-      "cert/cert_verify_proc_nss.h",
       "ssl/client_cert_store_nss.cc",
       "ssl/client_cert_store_nss.h",
     ]
+    if (!is_ios) {
+      # These files are part of the partial implementation of NSS on iOS so
+      # keep them in that case (even though use_nss_certs is not set).
+      sources -= [
+        "cert/cert_verify_proc_nss.cc",
+        "cert/cert_verify_proc_nss.h",
+      ]
+    }
     if (is_chromeos) {
       # These were already removed on non-ChromeOS.
       sources -= [