Add onconnect and ondisconnect events to navigator.usb.

Source/modules/webusb/USB.cpp

 // 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 "config.h"
 #include "modules/webusb/USB.h"
 
 #include "bindings/core/v8/CallbackPromiseAdapter.h"
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/dom/DOMException.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
+#include "modules/EventTargetModules.h"
 #include "modules/webusb/USBDevice.h"
 #include "modules/webusb/USBDeviceFilter.h"
 #include "modules/webusb/USBDeviceRequestOptions.h"
 #include "modules/webusb/USBError.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebVector.h"
 #include "public/platform/modules/webusb/WebUSBClient.h"
 #include "public/platform/modules/webusb/WebUSBDeviceFilter.h"
 #include "public/platform/modules/webusb/WebUSBDeviceRequestOptions.h"
 #include "public/platform/modules/webusb/WebUSBError.h"
@@ skipping 77 matching lines @@
     ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
 
     WebUSBDeviceRequestOptions webOptions;
     convertDeviceRequestOptions(options, &webOptions);
     client->requestDevice(webOptions, new CallbackPromiseAdapter<USBDevice, USBError>(resolver));
 
     return promise;
 }
 
+ExecutionContext* USB::executionContext() const
+{
+    return m_controller->frame()->document();

[haraken, 2015/08/20 00:31:31]

m_controller->frame() can be null if the frame was detached.

  return m_controller->frame() ? m_controller->frame()->document() : nullptr;

+}
+
+const AtomicString& USB::interfaceName() const
+{
+    return EventTargetNames::USB;
+}
+
 DEFINE_TRACE(USB)
 {
     visitor->trace(m_controller);
+    RefCountedGarbageCollectedEventTargetWithInlineData<USB>::trace(visitor);
 }
 
 } // namespace blink