Mojo: NULL -> nullptr in mojo/public/cpp outside of bindings.

mojo/public/cpp/application/lib/application_runner.cc

 // Copyright 2014 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 "mojo/public/cpp/application/application_runner.h"
 
 #include "mojo/public/cpp/application/application_delegate.h"
 #include "mojo/public/cpp/application/application_impl.h"
 #include "mojo/public/cpp/environment/environment.h"
 #include "mojo/public/cpp/utility/run_loop.h"
@@ skipping 12 matching lines @@
 MojoResult ApplicationRunner::Run(MojoHandle shell_handle) {
   Environment env;
   {
     RunLoop loop;
     ApplicationImpl app(delegate_,
         MakeScopedHandle(MessagePipeHandle(shell_handle)));
     loop.Run();
   }
 
   delete delegate_;
-  delegate_ = NULL;
+  delegate_ = nullptr;
   return MOJO_RESULT_OK;
 }
 
 }  // namespace mojo