Land prep work to enable NaCl in the Linux x64 GN builds.

ppapi/native_client/src/untrusted/irt_stub/BUILD.gn

Index: ppapi/native_client/src/untrusted/irt_stub/BUILD.gn
diff --git a/ppapi/native_client/src/untrusted/irt_stub/BUILD.gn b/ppapi/native_client/src/untrusted/irt_stub/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..b3f9ada96219280481ebe91048923de0e8b85d9b
--- /dev/null
+++ b/ppapi/native_client/src/untrusted/irt_stub/BUILD.gn
@@ -0,0 +1,15 @@
+# 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.
+
+assert(is_nacl,
+       "These targets must only be built using the untrusted NaCl toolchains.")
+
+static_library("ppapi_stub_lib") {

[brettw, 2015/02/25 21:27:29]

Almost all static libraries in GYP should be converted to source_set in GN. Some
exceptions are if we're distributing the actual static library. Can you check
the static libs you added to see if you're sure they need to be static
libraries?

[Dirk Pranke, 2015/02/25 21:37:41]

Will do.

+  sources = [
+    "ppapi_plugin_main.c",
+    "ppapi_plugin_start.c",
+    "plugin_main_irt.c",
+    "thread_creator.c",
+  ]
+}