Add WebUSB bindings and client interface

Source/modules/webusb/USBAlternateInterface.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/USBAlternateInterface.h"
+
+#include "modules/webusb/USBEndpoint.h"
+#include "modules/webusb/USBInterface.h"
+
+namespace blink {
+
+// static
+USBAlternateInterface* USBAlternateInterface::create(const USBInterface* interface, size_t alternateIndex)
+{
+    return new USBAlternateInterface(interface, alternateIndex);
+}
+
+USBAlternateInterface::USBAlternateInterface(const USBInterface* interface, size_t alternateIndex)
+    : m_interface(interface)
+    , m_alternateIndex(alternateIndex)
+{
+}
+
+const WebUSBDeviceInfo::AlternateInterface& USBAlternateInterface::info() const
+{
+    const WebUSBDeviceInfo::Interface& interfaceInfo = m_interface->info();
+    ASSERT(m_alternateIndex < interfaceInfo.alternates.size());
+    return interfaceInfo.alternates[m_alternateIndex];
+}
+
+uint8_t USBAlternateInterface::alternateSetting() const
+{
+    return info().alternateSetting;
+}
+
+uint8_t USBAlternateInterface::interfaceClass() const
+{
+    return info().classCode;
+}
+
+uint8_t USBAlternateInterface::interfaceSubclass() const
+{
+    return info().subclassCode;
+}
+
+uint8_t USBAlternateInterface::interfaceProtocol() const
+{
+    return info().protocolCode;
+}
+
+String USBAlternateInterface::interfaceName() const
+{
+    return info().interfaceName;
+}
+
+HeapVector<Member<USBEndpoint>> USBAlternateInterface::endpoints() const
+{
+    HeapVector<Member<USBEndpoint>> endpoints;
+    for (size_t i = 0; i < info().endpoints.size(); ++i)
+        endpoints.append(USBEndpoint::create(this, i));
+    return endpoints;
+}
+
+DEFINE_TRACE(USBAlternateInterface)
+{
+    visitor->trace(m_interface);

[Reilly Grant (use Gerrit), 2015/07/28 22:51:42]

#ifdef ENABLE(OILPAN)?

[Ken Rockot(use gerrit already), 2015/07/28 23:21:39]

Nah. Only necessary in cases where you're tracing a thing that is *WillBeGCed.
In the case of the USB interface object, its USBController instance may or may
not be garbage collected. I think I did this for compatibility with
LocalFrameLifeCycleObserver.

+}
+
+} // namespace blink