Test CL to demonstrate GN + hermetic toolchain

components/policy/BUILD.gn

Index: components/policy/BUILD.gn
diff --git a/components/policy/BUILD.gn b/components/policy/BUILD.gn
index 580ff4386a0435a37e7683b167ee0a5d58654d73..6d04696b50799ac8d614352fee5cd566e7f235e4 100644
--- a/components/policy/BUILD.gn
+++ b/components/policy/BUILD.gn
@@ -4,6 +4,7 @@
 
 import("//build/config/chrome_build.gni")
 import("//build/config/features.gni")
+import("//build/toolchain/toolchain.gni")
 import("//components/policy/resources/policy_templates.gni")
 import("//third_party/protobuf/proto_library.gni")
 import("//tools/grit/grit_rule.gni")
@@ -221,6 +222,8 @@ if (enable_configuration_policy) {
       ]
 
       args = [
+               "--developer_dir",
+               hermetic_xcode_path,
                "plutil",
                "-convert",
                "xml1",