Use the task scheduler in the new Windows USB backend

device/test/test_device_client.h

Index: device/test/test_device_client.h
diff --git a/device/test/test_device_client.h b/device/test/test_device_client.h
index 8393ae248e718456190407214981b3c404d30248..6d6df63bcad7d5a4245d578e6b2492703a5c32d1 100644
--- a/device/test/test_device_client.h
+++ b/device/test/test_device_client.h
@@ -4,13 +4,8 @@
 
 #include <memory>
 
-#include "base/memory/ref_counted.h"
 #include "device/base/device_client.h"
 
-namespace base {
-class SingleThreadTaskRunner;
-}
-
 namespace device {
 
 class HidService;
@@ -18,7 +13,7 @@ class UsbService;
 
 class TestDeviceClient : public DeviceClient {
  public:
-  TestDeviceClient(scoped_refptr<base::SingleThreadTaskRunner> task_runner);
+  TestDeviceClient();
 
   // Must be destroyed when tasks can still be posted to |task_runner|.
   ~TestDeviceClient() override;
@@ -29,7 +24,6 @@ class TestDeviceClient : public DeviceClient {
  private:
   std::unique_ptr<HidService> hid_service_;
   std::unique_ptr<UsbService> usb_service_;
-  scoped_refptr<base::SingleThreadTaskRunner> blocking_task_runner_;
 };
 
 }  // namespace device