Revert of Ensure BrowserThread::CurrentlyOn is correct through MessageLoop teardown

chrome/browser/browser_process_impl.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/browser_process_impl.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <map>
@@ skipping 238 matching lines @@
 
   update_client::UpdateQueryParams::SetDelegate(
       ChromeUpdateQueryParamsDelegate::GetInstance());
 
 #if !defined(OS_ANDROID)
   KeepAliveRegistry::GetInstance()->AddObserver(this);
 #endif  // !defined(OS_ANDROID)
 }
 
 BrowserProcessImpl::~BrowserProcessImpl() {
-#if defined(ENABLE_EXTENSIONS)
-  extensions::ExtensionsBrowserClient::Set(nullptr);
-#endif
-
 #if !defined(OS_ANDROID)
   KeepAliveRegistry::GetInstance()->RemoveObserver(this);
 #endif  // !defined(OS_ANDROID)
 
   tracked_objects::ThreadData::EnsureCleanupWasCalled(4);
 
   g_browser_process = NULL;
 }
 
 #if !defined(OS_ANDROID)
@@ skipping 1062 matching lines @@
 }
 
 void BrowserProcessImpl::OnAutoupdateTimer() {
   if (CanAutorestartForUpdate()) {
     DLOG(WARNING) << "Detected update.  Restarting browser.";
     RestartBackgroundInstance();
   }
 }
 
 #endif  // (defined(OS_WIN) || defined(OS_LINUX)) && !defined(OS_CHROMEOS)