Add copyright to gyp/codec.gyp.

Review URL: https://codereview.chromium.org/1023673010
diff --git a/gyp/codec.gyp b/gyp/codec.gyp
index c9e3ad8..29aebe9 100644
--- a/gyp/codec.gyp
+++ b/gyp/codec.gyp
@@ -1,3 +1,8 @@
+# Copyright 2015 Google Inc.
+#
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
 # GYP file for codec project.
 {
   'targets': [