Manage UsbService lifetime in DeviceClient implementations.

chrome/browser/chrome_device_client.cc

Index: chrome/browser/chrome_device_client.cc
diff --git a/chrome/browser/chrome_device_client.cc b/chrome/browser/chrome_device_client.cc
index 835a4c3a57782af555671849cdb89ca5fc3e9abd..0926a1fe9c57151533959b34a7bed99417618a87 100644
--- a/chrome/browser/chrome_device_client.cc
+++ b/chrome/browser/chrome_device_client.cc
@@ -17,8 +17,11 @@ ChromeDeviceClient::~ChromeDeviceClient() {}
 
 device::UsbService* ChromeDeviceClient::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* ChromeDeviceClient::GetHidService() {