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

plugin/win/config.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 39 matching lines @@
 #include <string>
 #include <iostream>
 #include <fstream>
 
 #include "base/logging.h"
 #include "plugin/cross/config.h"
 #include "plugin/cross/plugin_metrics.h"
 #include "core/cross/install_check.h"
 #include "third_party/nixysa/files/static_glue/npapi/common.h"
 
+namespace o3d {
+
 // Check Windows version.
 bool CheckOSVersion(NPP npp) {
   OSVERSIONINFOEX version = {sizeof(OSVERSIONINFOEX)};  // NOLINT
   GetVersionEx(reinterpret_cast<OSVERSIONINFO *>(&version));
   if (version.dwMajorVersion == 5 && version.dwMinorVersion == 1) {
     // NT 5.1 = Windows XP
     if (version.wServicePackMajor < 2) {
       // TODO: internationalize messages.
       std::string error = std::string("Windows XP Service Pack 2 is required.");
       if (!AskUser(npp, error)) return false;
@@ skipping 155 matching lines @@
     o3d::metric_browser_type = o3d::BROWSER_NAME_OPERA;
   } else if (std::string::npos != user_agent.find("Firefox")) {
     o3d::metric_browser_type = o3d::BROWSER_NAME_FIREFOX;
   } else if (std::string::npos != user_agent.find("MSIE")) {
     o3d::metric_browser_type = o3d::BROWSER_NAME_MSIE;
   } else {
     o3d::metric_browser_type = o3d::BROWSER_NAME_UNKNOWN;
   }
   return true;
 }
+}  // namespace o3d