Add comments setting emacs and vim tab width and expansion variables....

third_party/libpng/libpng.gyp

 # Copyright (c) 2009 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.
 
 {
   'variables': {
     'use_system_libpng%': 0,
   },
   'conditions': [
     ['use_system_libpng==0', {
@@ skipping 70 matching lines @@
             ],
             'libraries': [
               '<!@(pkg-config --libs-only-l libpng)',
             ],
           },
         },
       ],
     }],
   ],
 }
+
+# Local Variables:
+# tab-width:2
+# indent-tabs-mode:nil
+# End:
+# vim: set expandtab tabstop=2 shiftwidth=2: