Mojo: NULL -> nullptr in mojo/system and mojo/embedder.

mojo/system/message_in_transit.h

 // Copyright 2013 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.
 
 #ifndef MOJO_SYSTEM_MESSAGE_IN_TRANSIT_H_
 #define MOJO_SYSTEM_MESSAGE_IN_TRANSIT_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 88 matching lines @@
 
     // API parallel to that for |MessageInTransit| itself (mostly getters for
     // header data).
     const void* main_buffer() const { return buffer_; }
     size_t main_buffer_size() const {
       return RoundUpMessageAlignment(sizeof(Header) + header()->num_bytes);
     }
     const void* transport_data_buffer() const {
       return (total_size() > main_buffer_size())
                  ? static_cast<const char*>(buffer_) + main_buffer_size()
-                 : NULL;
+                 : nullptr;
     }
     size_t transport_data_buffer_size() const {
       return total_size() - main_buffer_size();
     }
     size_t total_size() const { return header()->total_size; }
     uint32_t num_bytes() const { return header()->num_bytes; }
     const void* bytes() const {
       return static_cast<const char*>(buffer_) + sizeof(Header);
     }
     Type type() const { return header()->type; }
@@ skipping 138 matching lines @@
   // some reason.)
   scoped_ptr<DispatcherVector> dispatchers_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageInTransit);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_MESSAGE_IN_TRANSIT_H_