Beginning work on GN build

build/linux/unbundle/libevent.gn

Index: build/linux/unbundle/libevent.gn
diff --git a/build/linux/unbundle/libevent.gn b/build/linux/unbundle/libevent.gn
new file mode 100644
index 0000000000000000000000000000000000000000..47e48e9b9927cd25045b67faae928961863a0a18
--- /dev/null
+++ b/build/linux/unbundle/libevent.gn
@@ -0,0 +1,17 @@
+# Copyright 2016 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/shim_headers.gni")
+
+shim_headers("libevent_shim") {
+  root_path = "."
+  headers = [ "event.h" ]
+}
+
+source_set("libevent") {
+  deps = [
+    ":libevent_shim",
+  ]
+  libs = [ "event" ]
+}