Implement WebUSBClient::setObserver in WebUSBClientImpl.

content/renderer/usb/web_usb_client_impl.cc

 // 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.
 
 #include "content/renderer/usb/web_usb_client_impl.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/move.h"
@@ skipping 80 matching lines @@
 }
 
 void WebUSBClientImpl::requestDevice(
     const blink::WebUSBDeviceRequestOptions& options,
     blink::WebUSBClientRequestDeviceCallbacks* callbacks) {
   callbacks->onError(blink::WebUSBError(blink::WebUSBError::Error::Service,
                                         base::UTF8ToUTF16("Not implemented.")));
   delete callbacks;
 }
 
+void WebUSBClientImpl::setObserver(Observer* observer) {
+  if (!observer_) {
+    // Set up two sequential calls to GetDeviceChanges to avoid latency.
+    device_manager_->GetDeviceChanges(base::Bind(
+        &WebUSBClientImpl::OnDeviceChangeNotification, base::Unretained(this)));
+    device_manager_->GetDeviceChanges(base::Bind(
+        &WebUSBClientImpl::OnDeviceChangeNotification, base::Unretained(this)));
+  }
+
+  observer_ = observer;
+}
+
+void WebUSBClientImpl::OnDeviceChangeNotification(
+    device::usb::DeviceChangeNotificationPtr notification) {
+  if (!observer_)
+    return;
+
+  device_manager_->GetDeviceChanges(base::Bind(
+      &WebUSBClientImpl::OnDeviceChangeNotification, base::Unretained(this)));
+  for (size_t i = 0; i < notification->devices_added.size(); ++i) {
+    device::usb::DeviceManagerPtr device_manager;
+    mojo::ConnectToService(device_services_.get(), &device_manager);
+    observer_->onDeviceConnected(blink::adoptWebPtr(new WebUSBDeviceImpl(
+        device_manager.Pass(), mojo::ConvertTo<blink::WebUSBDeviceInfo>(
+                                   notification->devices_added[i]))));
+  }
+  for (size_t i = 0; i < notification->devices_removed.size(); ++i) {
+    device::usb::DeviceManagerPtr device_manager;
+    mojo::ConnectToService(device_services_.get(), &device_manager);
+    observer_->onDeviceDisconnected(blink::adoptWebPtr(new WebUSBDeviceImpl(
+        device_manager.Pass(), mojo::ConvertTo<blink::WebUSBDeviceInfo>(
+                                   notification->devices_removed[i]))));
+  }
+}
+
 }  // namespace content