Manage UsbService lifetime in DeviceClient implementations.

extensions/shell/browser/shell_device_client.cc

 // Copyright 2014 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 "extensions/shell/browser/shell_device_client.h"
 
 #include "base/logging.h"
 #include "content/public/browser/browser_thread.h"
 #include "device/hid/hid_service.h"
 #include "device/usb/usb_service.h"
 
 using content::BrowserThread;
 
 namespace extensions {
 
 ShellDeviceClient::ShellDeviceClient() {}
 
 ShellDeviceClient::~ShellDeviceClient() {}
 
 device::UsbService* ShellDeviceClient::GetUsbService() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  return device::UsbService::GetInstance(
-      BrowserThread::GetMessageLoopProxyForThread(BrowserThread::FILE));
+
+  if (!usb_service_) {
+    usb_service_ = device::UsbService::Create(
+        BrowserThread::GetMessageLoopProxyForThread(BrowserThread::FILE));
+  }
+  return usb_service_.get();
 }
 
 device::HidService* ShellDeviceClient::GetHidService() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   return device::HidService::GetInstance(
       BrowserThread::GetMessageLoopProxyForThread(BrowserThread::FILE));
 }
 
 }