Manage UsbService lifetime in DeviceClient implementations.

extensions/shell/browser/shell_device_client.cc

Index: extensions/shell/browser/shell_device_client.cc
diff --git a/extensions/shell/browser/shell_device_client.cc b/extensions/shell/browser/shell_device_client.cc
index 5dd1c6b689755b85d1c2874c38034b2554f87eb0..ae006661e78193d96cc7a122b1ef8f031b028407 100644
--- a/extensions/shell/browser/shell_device_client.cc
+++ b/extensions/shell/browser/shell_device_client.cc
@@ -19,8 +19,12 @@ 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() {