Implement unregisterProtocolHandler() function on CUSTOM_SCHEME_HANDLER

Source/web/ChromeClientImpl.cpp

Index: Source/web/ChromeClientImpl.cpp
diff --git a/Source/web/ChromeClientImpl.cpp b/Source/web/ChromeClientImpl.cpp
index a567df5fb456590ea758bd5021d11a271bdce7d8..0336018b306ee18ed9a6a454638fed3e2fa66468 100644
--- a/Source/web/ChromeClientImpl.cpp
+++ b/Source/web/ChromeClientImpl.cpp
@@ -1013,6 +1013,19 @@ void NavigatorContentUtilsClientImpl::registerProtocolHandler(const String& sche
 {
     m_webView->client()->registerProtocolHandler(scheme, baseURL, url, title);
 }
+
+#if ENABLE(CUSTOM_SCHEME_HANDLER)
+NavigatorContentUtilsClient::CustomHandlersState NavigatorContentUtilsClientImpl::isProtocolHandlerRegistered(const String& scheme, const String& baseURL, const String& url)
+{
+    notImplemented();
+    return NavigatorContentUtilsClient::CustomHandlersDeclined;
+}
+
+void NavigatorContentUtilsClientImpl::unregisterProtocolHandler(const String& scheme, const String& baseURL, const String& url)
+{
+    m_webView->client()->unregisterProtocolHandler(scheme, baseURL, url);
+}
+#endif
 #endif
 
 } // namespace WebKit