Implement USB connection events through the WebUSB client interface.

Source/modules/webusb/USBConnectionEvent.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 USBConnectionEvent_h
 #define USBConnectionEvent_h
 
 #include "modules/EventModules.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class USBConnectionEventInit;
 class USBDevice;
 
 class USBConnectionEvent final : public Event {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static USBConnectionEvent* create(const AtomicString& type, const USBConnectionEventInit&);
-    static USBConnectionEvent* create(const AtomicString& type, USBDevice*);
+    static PassRefPtrWillBeRawPtr<USBConnectionEvent> create(const AtomicString& type, const USBConnectionEventInit&);
+    static PassRefPtrWillBeRawPtr<USBConnectionEvent> create(const AtomicString& type, USBDevice*);
 
     USBConnectionEvent(const AtomicString& type, const USBConnectionEventInit&);
     USBConnectionEvent(const AtomicString& type, USBDevice*);
 
     USBDevice* device() const { return m_device; }
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     PersistentWillBeMember<USBDevice> m_device;
 };
 
 } // namespace blink
 
 #endif // USBConnectionEvent_h