Extract //device/usb mocks so that they can be shared.

device/usb/mock_usb_service.h

+// Copyright 2015 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.
+
+#ifndef DEVICE_USB_MOCK_USB_SERVICE_H_
+#define DEVICE_USB_MOCK_USB_SERVICE_H_
+
+#include "device/usb/usb_service.h"
+
+#include "testing/gmock/include/gmock/gmock.h"
+
+namespace device {
+
+class MockUsbService : public UsbService {
+ public:
+  MockUsbService();
+  ~MockUsbService() override;
+
+  void AddDevice(scoped_refptr<UsbDevice> device);
+  void RemoveDevice(scoped_refptr<UsbDevice> device);
+
+ protected:
+  // UsbService implementation:
+  scoped_refptr<UsbDevice> GetDeviceById(uint32 unique_id) override;
+  void GetDevices(const GetDevicesCallback& callback) override;
+
+  std::map<uint32, scoped_refptr<UsbDevice>> devices_;
+};
+
+}  // namespace device
+
+#endif  // DEVICE_USB_MOCK_USB_SERVICE_H_