Introduce unregisterProtocolHandler() and isProtocolHandlerRegistered() webview API

Source/web/ChromeClientImpl.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 1015 matching lines @@
 {
 }
 
 void NavigatorContentUtilsClientImpl::registerProtocolHandler(const String& scheme, const String& baseURL, const String& url, const String& title)
 {
     m_webView->client()->registerProtocolHandler(scheme, baseURL, url, title);
 }
 
 NavigatorContentUtilsClient::CustomHandlersState NavigatorContentUtilsClientImpl::isProtocolHandlerRegistered(const String& scheme, const String& baseURL, const String& url)
 {
-    notImplemented();
-    return NavigatorContentUtilsClient::CustomHandlersDeclined;
+    return static_cast<NavigatorContentUtilsClient::CustomHandlersState>(m_webView->client()->isProtocolHandlerRegistered(scheme, baseURL, url));
 }
 
 void NavigatorContentUtilsClientImpl::unregisterProtocolHandler(const String& scheme, const String& baseURL, const String& url)
 {
-    notImplemented();
+    m_webView->client()->unregisterProtocolHandler(scheme, baseURL, url);
 }
 
 } // namespace blink