Add WebAuthn bindings and client interface.

third_party/WebKit/Source/modules/webauth/ScopedCredentialDescriptor.idl

Index: third_party/WebKit/Source/modules/webauth/ScopedCredentialDescriptor.idl
diff --git a/third_party/WebKit/Source/modules/webauth/ScopedCredentialDescriptor.idl b/third_party/WebKit/Source/modules/webauth/ScopedCredentialDescriptor.idl
new file mode 100644
index 0000000000000000000000000000000000000000..ccbd1544961ca719d70c2b58a7bfe8e29b08964b
--- /dev/null
+++ b/third_party/WebKit/Source/modules/webauth/ScopedCredentialDescriptor.idl
@@ -0,0 +1,19 @@
+// 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.
+
+// https://w3c.github.io/webauthn/#enumdef-externaltransport
+
+enum Transport {
+    "usb",
+    "nfc",
+    "ble"
+};
+
+// https://w3c.github.io/webauthn/#dictdef-scopedcredentialdescriptor
+
+dictionary ScopedCredentialDescriptor {
+    required ScopedCredentialType type;
+    required BufferSource id;
+    sequence<Transport> transports;
+};