Make AppShimHostManager a RefCountedThreadSafe.

chrome/browser/browser_process_platform_part_mac.mm

 // Copyright (c) 2013 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_platform_part_mac.h"
 
-#include "apps/app_shim/app_shim_host_manager_mac.h"
 #include "chrome/browser/chrome_browser_application_mac.h"
 #include "chrome/browser/ui/app_list/app_list_service.h"
 
 BrowserProcessPlatformPart::BrowserProcessPlatformPart() {
 }
 
 BrowserProcessPlatformPart::~BrowserProcessPlatformPart() {
 }
 
 void BrowserProcessPlatformPart::StartTearDown() {
-  app_shim_host_manager_.reset();
+  app_shim_host_manager_ = NULL;
 }
 
 void BrowserProcessPlatformPart::AttemptExit() {
   // On the Mac, the application continues to run once all windows are closed.
   // Terminate will result in a CloseAllBrowsers() call, and once (and if)
   // that is done, will cause the application to exit cleanly.
   chrome_browser_application_mac::Terminate();
 }
 
 void BrowserProcessPlatformPart::PreMainMessageLoopRun() {
-  app_shim_host_manager_.reset(new AppShimHostManager);
+  app_shim_host_manager_ = new AppShimHostManager;
   AppListService::InitAll(NULL);
 }
 
 AppShimHostManager* BrowserProcessPlatformPart::app_shim_host_manager() {
   return app_shim_host_manager_.get();
 }