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

ppapi/native_client/tests/ppapi_browser/ppp_instance/ppapi_ppp_instance.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 startsWith(str, prefix) {
   return (str.indexOf(prefix) === 0);
 }
 
 function setupTests(tester, plugin) {
   //////////////////////////////////////////////////////////////////////////////
   // Test Helpers
@@ skipping 48 matching lines @@
   });
 
   // PPP_Instance::HandleDocumentLoad is only used with full-frame plugins.
   // This is tested in tests/ppapi_browser/extension_mime_handler/
 
   // PPP_Instance::DidDestroy is never invoked in the untrusted code.
   // We could wait for a crash event from it, but CallOnMainThread semantics
   // on shutdown are still buggy, so it might never come even if the function
   // triggered. Plus waiting for something not to happen makes the test flaky.
 }