Add a new GetInstance() method for singleton classes, take 2.

chrome/test/webdriver/session_manager.cc

 // Copyright (c) 2010 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 "chrome/test/webdriver/session_manager.h"
 
 #ifdef OS_POSIX
   #include <netdb.h>
   #include <unistd.h>
   #include <arpa/inet.h>
@@ skipping 165 matching lines @@
 Session* SessionManager::GetSession(const std::string& id) const {
   std::map<std::string, Session*>::const_iterator it;
   it = map_.find(id);
   if (it == map_.end()) {
     VLOG(1) << "No such session with ID " << id;
     return NULL;
   }
   return it->second;
 }
 
+// static
+SessionManager* SessionManager::GetInstance() {
+  return Singleton<SessionManager>::get();
+}
+
 }  // namespace webdriver