Implement the rest of the PPAPI examples in the GN build.

ppapi/examples/scripting/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("//ppapi/examples/ppapi_example.gni")
 
-ppapi_example("audio") {
-  output_name = "ppapi_example_audio"
+ppapi_example("scripting") {
+  output_name = "ppapi_example_post_message"
   sources = [
-    "audio.cc",
+    "post_message.cc",
   ]
   deps = [
     "//ppapi/cpp",
   ]
 }