Add copyright headers to remaining gyp files.

gyp/SimpleCocoaApp.gyp

+# Copyright 2015 Google Inc.
+#
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
 {
   'targets': [
     {
       'target_name': 'SimpleCocoaApp',
       'type': 'executable',
       'mac_bundle' : 1,
       'include_dirs' : [
         '../experimental/SimpleCocoaApp/',
       ],
       'sources': [
@@ skipping 34 matching lines @@
             'INFOPLIST_FILE' : '../experimental/SimpleCocoaApp/SimpleApp-Info.plist',
           },
           'mac_bundle_resources' : [
             '../experimental/SimpleCocoaApp/SimpleApp.xib',
           ],
         }],
       ],
     },
   ],
 }