In preparation for becoming an internal plugin in chrome I did these things:...

plugin/cross/config_common.cc

 /*
  * Copyright 2009, Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 34 matching lines @@
 
 #include "base/logging.h"
 #include "core/cross/install_check.h"
 #include "plugin/cross/config.h"
 #include "plugin/cross/o3d_glue.h"
 #include "core/cross/error.h"
 #include "third_party/nixysa/files/static_glue/npapi/common.h"
 
 using glue::_o3d::GetServiceLocator;
 
+namespace o3d {
+
 // Gets the value of "navigator.userAgent" in the JavaScript context, which
 // contains the user agent string.
 std::string GetUserAgent(NPP npp) {
   GLUE_PROFILE_START(npp, "NPN_UserAgent");
   const char* user_agent = NPN_UserAgent(npp);
   GLUE_PROFILE_STOP(npp, "NPN_UserAgent");
   std::string uagent_string;
   if (user_agent) {
     uagent_string = std::string(user_agent);
   }
@@ skipping 141 matching lines @@
       }
       return false;
     }
   }
 
   // Check User agent. Only Firefox, Chrome and IE are supported.
   std::string user_agent = GetUserAgent(npp);
   if (!CheckUserAgent(npp, user_agent)) return false;
   return true;
 }
+}  // namespace o3d