Initial skeletal implementation of the PrincipalService. Also, use the Login()/GetUserBlessing()

services/vanadium/security/BUILD.gn

Index: services/vanadium/security/BUILD.gn
diff --git a/services/vanadium/security/BUILD.gn b/services/vanadium/security/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..3ba6f0221894ca439c4c6809a29d23c525acf346
--- /dev/null
+++ b/services/vanadium/security/BUILD.gn
@@ -0,0 +1,21 @@
+# Copyright 2015 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("//mojo/go/rules.gni")
+
+group("go") {
+  assert(go_build_tool != "")
+  deps = [
+    ":go_principal_service",
+  ]
+}
+
+go_mojo_application("go_principal_service") {
+  sources = [
+    "principal_service.go",
+  ]
+  deps = [
+    "//mojo/services/vanadium/security/public/interfaces",
+  ]
+}