Implement net in GN build.

crypto/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/crypto.gni")
 
 component("crypto") {
   output_name = "crcrypto"  # Avoid colliding with OpenSSL's libcrypto.
   sources = [
     "apple_keychain.h",
@@ skipping 246 matching lines @@
 # according to the state of the crypto flags. A target just wanting to depend
 # on the current SSL library should just depend on this.
 group("platform") {
   if (use_openssl) {
     deps = [ "//third_party/openssl" ]
   } else {
     deps = [ "//net/third_party/nss/ssl:libssl" ]
     if (is_linux) {
       # On Linux, we use the system NSS (excepting SSL where we always use our
       # own).
+      #
+      # We always need our SSL header search path to come before the system one
+      # so our versions are used. The libssl target will add the search path we
+      # want, but according to GN's ordering rules, direct_dependent_configs'
+      # search path will get applied before ones inherited from our
+      # dependencies. Therefore, we need to explicitly list our custom libssl's
+      # config here before the system one.
       direct_dependent_configs = [
-        "//third_party/nss:system_nss_no_ssl_config"
+        "//net/third_party/nss/ssl:ssl_config",
+        "//third_party/nss:system_nss_no_ssl_config",
       ]
     } else {
       # Non-Linux platforms use the hermetic NSS from the tree.
       deps += [
         "//third_party/nss:nspr",
         "//third_party/nss:nss",
       ]
     }
   }
 }