Implement WebUSBClient::setObserver in WebUSBClientImpl.

content/renderer/usb/web_usb_client_impl.cc

Index: content/renderer/usb/web_usb_client_impl.cc
diff --git a/content/renderer/usb/web_usb_client_impl.cc b/content/renderer/usb/web_usb_client_impl.cc
index ac4f681a3ff34f49702e6c7e3a7c410f1524fabf..a1da1c86edb5fe0ce817afa52c997a5c8cf6b08d 100644
--- a/content/renderer/usb/web_usb_client_impl.cc
+++ b/content/renderer/usb/web_usb_client_impl.cc
@@ -98,4 +98,38 @@ void WebUSBClientImpl::requestDevice(
   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_) {

[Ken Rockot(use gerrit already), 2015/09/15 18:23:34]

minor nit: just return if !observer_? less whitespace for everyone!

[Reilly Grant (use Gerrit), 2015/09/15 19:49:54]

Done.

+    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