Implement WebUSBClient::setObserver in WebUSBClientImpl.

content/renderer/usb/web_usb_client_impl.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 CONTENT_RENDERER_USB_WEB_USB_CLIENT_IMPL_H_
 #define CONTENT_RENDERER_USB_WEB_USB_CLIENT_IMPL_H_
 
 #include "base/id_map.h"
 #include "base/macros.h"
 #include "device/devices_app/usb/public/interfaces/device_manager.mojom.h"
 #include "mojo/application/public/interfaces/service_provider.mojom.h"
 #include "third_party/WebKit/public/platform/modules/webusb/WebUSBClient.h"
 
 namespace content {
 
 class WebUSBClientImpl : public blink::WebUSBClient {
  public:
   explicit WebUSBClientImpl(mojo::ServiceProviderPtr device_services);
   ~WebUSBClientImpl() override;
 
  private:
   // blink::WebUSBClient implementation:
   void getDevices(blink::WebUSBClientGetDevicesCallbacks* callbacks) override;
   void requestDevice(
       const blink::WebUSBDeviceRequestOptions& options,
       blink::WebUSBClientRequestDeviceCallbacks* callbacks) override;
+  void setObserver(Observer* observer) override;
+
+  void OnDeviceChangeNotification(
+      device::usb::DeviceChangeNotificationPtr notification);
 
   mojo::ServiceProviderPtr device_services_;
   device::usb::DeviceManagerPtr device_manager_;
+  Observer* observer_ = nullptr;
 
   DISALLOW_COPY_AND_ASSIGN(WebUSBClientImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_USB_WEB_USB_CLIENT_IMPL_H_