Extract locking behaviour from ProcessSingleton.

chrome/browser/process_singleton.cc

-// Copyright (c) 2012 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/browser/process_singleton.h"
-
-void ProcessSingleton::Unlock() {
-    DCHECK(CalledOnValidThread());
-    locked_ = false;
-    foreground_window_ = NULL;
-    // Replay the command lines of the messages which were received while the
-    // ProcessSingleton was locked. Only replay each message once.
-    std::set<DelayedStartupMessage> replayed_messages;
-    for (std::vector<DelayedStartupMessage>::const_iterator it =
-             saved_startup_messages_.begin();
-         it != saved_startup_messages_.end(); ++it) {
-      if (replayed_messages.find(*it) !=
-          replayed_messages.end())
-        continue;
-      notification_callback_.Run(CommandLine(it->first), it->second);
-      replayed_messages.insert(*it);
-    }
-    saved_startup_messages_.clear();
-}