Make AppShimHostManager a RefCountedThreadSafe.

apps/app_shim/app_shim_host_manager_mac.mm

 // Copyright 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 "apps/app_shim/app_shim_host_manager_mac.h"
 
 #include "apps/app_shim/app_shim_handler_mac.h"
 #include "apps/app_shim/app_shim_host_mac.h"
 #include "base/bind.h"
 #include "base/files/file_path.h"
@@ skipping 13 matching lines @@
   (new AppShimHost)->ServeChannel(handle);
 }
 
 }  // namespace
 
 AppShimHostManager::AppShimHostManager() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   apps::AppShimHandler::SetDefaultHandler(&extension_app_shim_handler_);
   BrowserThread::PostTask(
       BrowserThread::FILE, FROM_HERE,
-      base::Bind(&AppShimHostManager::InitOnFileThread,
-          base::Unretained(this)));
+      base::Bind(&AppShimHostManager::InitOnFileThread, this));
 }
 
 AppShimHostManager::~AppShimHostManager() {
   apps::AppShimHandler::SetDefaultHandler(NULL);
 }
 
 void AppShimHostManager::InitOnFileThread() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
   base::FilePath user_data_dir;
   if (!PathService::Get(chrome::DIR_USER_DATA, &user_data_dir)) {
     LOG(ERROR) << "Couldn't get user data directory while creating App Shim "
                << "Host manager.";
     return;
   }
   base::FilePath socket_path =
       user_data_dir.Append(app_mode::kAppShimSocketName);
   factory_.reset(new IPC::ChannelFactory(socket_path, this));
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
-      base::Bind(&AppShimHostManager::ListenOnIOThread,
-          base::Unretained(this)));
+      base::Bind(&AppShimHostManager::ListenOnIOThread, this));
 }
 
 void AppShimHostManager::ListenOnIOThread() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   factory_->Listen();
 }
 
 void AppShimHostManager::OnClientConnected(
     const IPC::ChannelHandle& handle) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(&CreateAppShimHost, handle));
 }
 
 void AppShimHostManager::OnListenError() {
   // TODO(jeremya): set a timeout and attempt to reconstruct the channel.
 }