[webnfc]: Step 1: Add NavigatorNfc, Nfc and Layout tests.

Source/modules/nfc/NavigatorNFC.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 NavigatorNFC_h
+#define NavigatorNFC_h
+
+#include "platform/Supplementable.h"
+#include "platform/heap/Handle.h"
+
+namespace blink {
+
+class NFC;
+class Navigator;
+class ExecutionContext;
+
+class NavigatorNFC final
+    : public GarbageCollectedFinalized<NavigatorNFC>

[Jeffrey Yasskin, 2015/08/18 17:48:59]

This class has no destructor, so it probably can be just GarbageCollected and
not finalized?

[riju_, 2015/08/19 08:41:22]

Done.

+    , public HeapSupplement<Navigator> {
+    USING_GARBAGE_COLLECTED_MIXIN(NavigatorNFC);
+
+public:
+    // Gets, or creates, NavigatorNFC supplement on Navigator.
+    static NavigatorNFC& from(Navigator&);
+
+    static NFC* nfc(ExecutionContext*, Navigator&);
+
+    DECLARE_TRACE();
+
+private:
+    NavigatorNFC();
+    static const char* supplementName();
+
+    Member<NFC> m_nfc;
+};
+
+} // namespace blink
+
+#endif // NavigatorNFC_h