Update Native Client Authors to be Chromium Authors for the code moved from the

ppapi/native_client/tests/ppapi_browser/ppb_scrollbar/ppapi_ppb_scrollbar.js

-// Copyright (c) 2011 The Native Client Authors. All rights reserved.
+// Copyright (c) 2011 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.
 
 function setupTests(tester, plugin) {
   // This function takes an array of messages and asserts that the nexe
   // calls PostMessage with each of these messages, in order.
   function expectMessages(test, plugin, messages) {
     test.assert(messages.length > 0, 'Must provide at least one message');
     var listener = test.wrap(function(message) {
       plugin.removeEventListener('message', listener, false);
@@ skipping 19 matching lines @@
     });
   }
 
   addTest('TestCreate');
   addTest('TestGetThickness');
   addTest('TestValue');
   addTest('TestSetDocumentSize');
   addTest('TestSetTickMarks');
   addTest('TestScrollBy');
 }