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

ppapi/examples/compositor/BUILD.gn

Index: ppapi/examples/compositor/BUILD.gn
diff --git a/ppapi/examples/audio/BUILD.gn b/ppapi/examples/compositor/BUILD.gn
similarity index 60%
copy from ppapi/examples/audio/BUILD.gn
copy to ppapi/examples/compositor/BUILD.gn
index f1243d68bbba082d4b7194729ad0d2cc5993220f..d7007a111eb88fe3a1a00fcbc4ffce85bab70c84 100644
--- a/ppapi/examples/audio/BUILD.gn
+++ b/ppapi/examples/compositor/BUILD.gn
@@ -1,15 +1,18 @@
 # 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.
+# found in the LICENSE file.
 
 import("//ppapi/examples/ppapi_example.gni")
 
-ppapi_example("audio") {
-  output_name = "ppapi_example_audio"
+ppapi_example("compositor") {
+  output_name = "ppapi_example_compositor"
   sources = [
-    "audio.cc",
+    "compositor.cc",
+    "spinning_cube.cc",
+    "spinning_cube.h",
   ]
   deps = [
     "//ppapi/cpp",
+    "//ppapi/lib/gl/gles2",
   ]
 }