headless: Add a small C++ example application

headless/BUILD.gn

 # 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("//build/config/chrome_build.gni")
 import("//headless/headless.gni")
 import("//build/util/process_version.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//testing/test.gni")
 import("//tools/grit/grit_rule.gni")
@@ skipping 305 matching lines @@
   }
 
   configs += [ ":headless_implementation" ]
 }
 
 group("headless_tests") {
   testonly = true
 
   deps = [
     ":headless_browsertests",
+    ":headless_example",
     ":headless_unittests",
   ]
 }
 
 test("headless_unittests") {
   sources = [
     "public/domains/types_unittest.cc",
     "public/util/deterministic_dispatcher_test.cc",
     "public/util/error_reporter_unittest.cc",
     "public/util/expedited_dispatcher_test.cc",
@@ skipping 116 matching lines @@
 }
 
 process_version("version_header") {
   template_file = "public/version.h.in"
   sources = [
     "//build/util/LASTCHANGE",
     "//chrome/VERSION",
   ]
   output = "$target_gen_dir/public/version.h"
 }
+
+executable("headless_example") {
+  sources = [
+    "app/headless_example.cc",
+  ]
+
+  deps = [
+    "//headless:headless_shell_lib",
+  ]
+}