Remove unused ImmediateShutdownAndExitProcess()

content/public/browser/browser_shutdown.h

-// 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.
-
-#ifndef CONTENT_PUBLIC_BROWSER_BROWSER_SHUTDOWN_H_
-#define CONTENT_PUBLIC_BROWSER_BROWSER_SHUTDOWN_H_
-
-#include "content/common/content_export.h"
-
-namespace content {
-
-// This can be used for as-fast-as-possible shutdown, in cases where
-// time for shutdown is limited and we just need to write out as much
-// data as possible before our time runs out.
-//
-// This causes the shutdown sequence embodied by
-// BrowserMainParts::PostMainMessageLoopRun through
-// BrowserMainParts::PostDestroyThreads to occur, i.e. we pretend the
-// message loop finished, all threads are stopped in sequence and then
-// PostDestroyThreads is called.
-//
-// As this violates the normal order of shutdown, likely leaving the
-// process in a bad state, the last thing this function does is
-// terminate the process (right after calling
-// BrowserMainParts::PostDestroyThreads).
-CONTENT_EXPORT void ImmediateShutdownAndExitProcess();
-
-}  // namespace content
-
-#endif  // CONTENT_PUBLIC_BROWSER_BROWSER_SHUTDOWN_H_