This CL implements the second TODO item of issue 12343:...

chrome/browser/process_singleton.h

 // Copyright (c) 2009 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 CHROME_BROWSER_PROCESS_SINGLETON_H_
 #define CHROME_BROWSER_PROCESS_SINGLETON_H_
 
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
@@ skipping 74 matching lines @@
                                         WPARAM wparam,
                                         LPARAM lparam) {
     ProcessSingleton* msg_wnd = reinterpret_cast<ProcessSingleton*>(
         GetWindowLongPtr(hwnd, GWLP_USERDATA));
     return msg_wnd->WndProc(hwnd, message, wparam, lparam);
   }
 
   HWND remote_window_;  // The HWND_MESSAGE of another browser.
   HWND window_;  // The HWND_MESSAGE window.
 #elif defined(OS_LINUX)
-  // Set up a socket and sockaddr appropriate for messaging.
-  void SetupSocket(int* sock, struct sockaddr_un* addr);
-
   // Path in file system to the socket.
   FilePath socket_path_;
 
   // Helper class for linux specific messages.  LinuxWatcher is ref counted
   // because it posts messages between threads.
   class LinuxWatcher;
   scoped_refptr<LinuxWatcher> watcher_;
 #endif
 
+#if defined(OS_WIN) || defined(OS_LINUX)
+  // Timeout for the current browser process to respond. 20 seconds should be
+  // enough. It's only used in Windows and Linux implementations.
+  static const int kTimeoutInSeconds = 20;
+#endif
+
   DISALLOW_COPY_AND_ASSIGN(ProcessSingleton);
 };
 
 #endif  // CHROME_BROWSER_PROCESS_SINGLETON_H_