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

ppapi/native_client/tests/ppapi_browser/ppb_graphics2d/ppapi_ppb_graphics2d.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.
 //
 // Test cases for PPB_Graphics2D functions.
 // As most of them return void, the test automatically confirms that
 // there is no crash while requiring a visual inspection of the painted output.
 
 #include <string.h>
 
 #include "native_client/src/include/nacl_macros.h"
@@ skipping 532 matching lines @@
   RegisterTest("TestScrollEntire", TestScrollEntire);
   RegisterTest("TestReplaceContents", TestReplaceContents);
   RegisterTest("TestFlush", TestFlush);
   RegisterTest("TestFlushAnimation", TestFlushAnimation);
   RegisterTest("TestStress", TestStress);
 }
 
 void SetupPluginInterfaces() {
   // none
 }