Track USB alternate interface state in Blink.

third_party/WebKit/Source/modules/webusb/USBInterface.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 USBInterface_h
 #define USBInterface_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "platform/heap/Heap.h"
 #include "public/platform/modules/webusb/WebUSBDeviceInfo.h"
@@ skipping 11 matching lines @@
     DEFINE_WRAPPERTYPEINFO();
 public:
     static USBInterface* create(const USBConfiguration*, size_t interfaceIndex);
     static USBInterface* create(const USBConfiguration*, size_t interfaceNumber, ExceptionState&);
 
     USBInterface(const USBDevice*, size_t configurationIndex, size_t interfaceIndex);
 
     const WebUSBDeviceInfo::Interface& info() const;
 
     uint8_t interfaceNumber() const;
+    USBAlternateInterface* alternate() const;
     HeapVector<Member<USBAlternateInterface>> alternates() const;
     bool claimed() const;
 
     DECLARE_TRACE();
 
 private:
     Member<const USBDevice> m_device;
     const size_t m_configurationIndex;
     const size_t m_interfaceIndex;
 };
 
 } // namespace blink
 
 #endif // USBInterface_h