[webnfc] Add public interfaces.

third_party/WebKit/public/platform/modules/nfc/WebNFCObserver.h

Index: third_party/WebKit/public/platform/modules/nfc/WebNFCObserver.h
diff --git a/third_party/WebKit/public/platform/modules/nfc/WebNFCObserver.h b/third_party/WebKit/public/platform/modules/nfc/WebNFCObserver.h
new file mode 100644
index 0000000000000000000000000000000000000000..86e9d5807d7662526479136c9bbce5c1f43a0421
--- /dev/null
+++ b/third_party/WebKit/public/platform/modules/nfc/WebNFCObserver.h
@@ -0,0 +1,27 @@
+// 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 WebNFCObserver_h
+#define WebNFCObserver_h
+
+namespace blink {
+
+struct WebNFCMessage;
+
+// Observer interface that should be implemented in order to get notification
+// about triggered NFC watch.
+class WebNFCObserver {
+public:
+    virtual ~WebNFCObserver() { }
+
+    // The id is an identifier of the registered NFC watch that was obtained after
+    // calling watch method (https://w3c.github.io/web-nfc/#the-watch-method).
+    // The WebNFCMessage that matches NFC watch filtering criteria is provided to the callback.
+    // See https://w3c.github.io/web-nfc/#idl-def-messagecallback
+    virtual void onWatch(long id, const WebNFCMessage&) = 0;
+};
+
+} // namespace blink
+
+#endif // WebNFCObserver_h