Support building BoringSSL with NSS certificates.

crypto/BUILD.gn

Index: crypto/BUILD.gn
diff --git a/crypto/BUILD.gn b/crypto/BUILD.gn
index f6c45aad72d3b55c99334d9c91bdca793a4699b1..65687570931a2449ffeb86ad75f482216809a211 100644
--- a/crypto/BUILD.gn
+++ b/crypto/BUILD.gn
@@ -138,9 +138,6 @@ component("crypto") {
       "ec_signature_creator_nss.cc",
       "encryptor_nss.cc",
       "hmac_nss.cc",
-      "nss_util.cc",
-      "nss_util.h",
-      "nss_util_internal.h",
       "rsa_private_key_nss.cc",
       "secure_hash_default.cc",
       "signature_creator_nss.cc",
@@ -172,6 +169,14 @@ component("crypto") {
     ]
   }
 
+  if (use_openssl && !use_nss_certs) {
+    sources -= [
+      "nss_util.cc",
+      "nss_util.h",
+      "nss_util_internal.h",
+    ]
+  }
+
   defines = [ "CRYPTO_IMPLEMENTATION" ]
 }
 
@@ -233,13 +238,15 @@ if (!is_win) {
       "symmetric_key_unittest.cc",
     ]
 
-    if (use_openssl || !is_linux) {
+    if (use_openssl || !use_nss_certs) {
       sources -= [ "rsa_private_key_nss_unittest.cc" ]
     }
 
-    if (use_openssl) {
+    if (!use_nss_certs) {
       sources -= [ "nss_util_unittest.cc" ]
-    } else {
+    }
+
+    if (!use_openssl) {
       sources -= [ "openssl_bio_string_unittest.cc" ]
     }
 
@@ -300,6 +307,9 @@ group("platform") {
     deps = [
       "//net/third_party/nss/ssl:libssl",
     ]
+  }
+
+  if (use_nss_certs || !use_openssl) {
     if (is_linux) {
       # On Linux, we use the system NSS (excepting SSL where we always use our
       # own).