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

ppapi/examples/video_decode/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")
+
+group("video_decode") {
+  testonly = true
+  deps = [
+    ":dev",
+    ":stable",
+  ]
+}
+
+ppapi_example("dev") {
+  output_name = "ppapi_example_video_decode_dev"
+  sources = [
+    "video_decode_dev.cc",
+    "testdata.h",
+  ]
+  deps = [
+    "//ppapi/cpp",
+    "//ppapi/lib/gl/gles2",
+  ]
+}
+
+ppapi_example("stable") {
+  output_name = "ppapi_example_video_decode"
+  sources = [
+    "video_decode.cc",
+    "testdata.h",
+  ]
+  deps = [
+    "//ppapi/cpp",
+    "//ppapi/lib/gl/gles2",
+  ]
+}