[webnfc] Add default implementation for nfc mojo service.

device/nfc/nfc_impl.h

Index: device/nfc/nfc_impl.h
diff --git a/device/nfc/nfc_impl.h b/device/nfc/nfc_impl.h
new file mode 100644
index 0000000000000000000000000000000000000000..c6b8a4e4bfa3e251379eb34c3c4e56c0acb8cee0
--- /dev/null
+++ b/device/nfc/nfc_impl.h
@@ -0,0 +1,20 @@
+// Copyright 2016 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 DEVICE_NFC_NFC_IMPL_H_
+#define DEVICE_NFC_NFC_IMPL_H_
+
+#include "device/nfc/nfc.mojom.h"
+#include "device/nfc/nfc_export.h"
+
+namespace device {
+
+class NFCImpl {
+ public:
+  DEVICE_NFC_EXPORT static void Create(mojo::InterfaceRequest<NFC> request);
+};
+
+}  // namespace device
+
+#endif  // DEVICE_NFC_NFC_IMPL_H_