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

ppapi/native_client/tests/ppapi_browser/ppb_pdf/ppapi_ppb_pdf.cc

-// 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.
 
 #include <string.h>
 #include <string>
 
 #include "native_client/src/include/nacl_macros.h"
 #include "native_client/src/shared/platform/nacl_check.h"
 #include "native_client/tests/ppapi_test_lib/get_browser_interface.h"
 #include "native_client/tests/ppapi_test_lib/test_interface.h"
@@ skipping 238 matching lines @@
                TestUserMetricsRecordAction);
   RegisterTest("TestHasUnsupportedFeature",
                TestHasUnsupportedFeature);
   RegisterTest("TestSaveAs",
                 TestSaveAs);
 }
 
 void SetupPluginInterfaces() {
 }