Add a new GetInstance() method for singleton classes used in chrome/browser files.

chrome/browser/zygote_host_linux.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_ZYGOTE_HOST_LINUX_H_
 #define CHROME_BROWSER_ZYGOTE_HOST_LINUX_H_
 #pragma once
 
 #include <unistd.h>
 
 #include <string>
 #include <vector>
 
 #include "base/global_descriptors_posix.h"
 #include "base/lock.h"
 #include "base/process.h"
 
 template<typename Type>
 struct DefaultSingletonTraits;
 
 static const char kZygoteMagic[] = "ZYGOTE_OK";
 
 // http://code.google.com/p/chromium/wiki/LinuxZygote
 
 // The zygote host is the interface, in the browser process, to the zygote
 // process.
 class ZygoteHost {
  public:
+  // Returns the singleton instance.
+  static ZygoteHost* GetInstance();
+
   void Init(const std::string& sandbox_cmd);
 
   // Tries to start a renderer process.  Returns its pid on success, otherwise
   // base::kNullProcessHandle;
   pid_t ForkRenderer(const std::vector<std::string>& command_line,
                      const base::GlobalDescriptors::Mapping& mapping);
   void EnsureProcessTerminated(pid_t process);
 
   // Get the termination status (exit code) of the process and return true if
   // the status indicates the process crashed. |child_exited| is set to true
@@ skipping 45 matching lines @@
   Lock control_lock_;
   pid_t pid_;
   bool init_;
   bool using_suid_sandbox_;
   std::string sandbox_binary_;
   bool have_read_sandbox_status_word_;
   int sandbox_status_;
 };
 
 #endif  // CHROME_BROWSER_ZYGOTE_HOST_LINUX_H_