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 50c4c283d6ce26e013c5249aee1c0bcb4d5f7305..b09b1a89a8cc3bc8ef2e0ad0eb019307148370f5 100644
--- a/Source/web/ChromeClientImpl.cpp
+++ b/Source/web/ChromeClientImpl.cpp
@@ -86,6 +86,7 @@
 #include "core/platform/Cursor.h"
 #include "core/platform/DateTimeChooser.h"
 #include "core/platform/FileChooser.h"
+#include "core/platform/NotImplemented.h"
 #include "core/platform/PlatformScreen.h"
 #include "core/platform/chromium/support/WrappedResourceRequest.h"
 #include "core/platform/graphics/FloatRect.h"
@@ -1007,6 +1008,19 @@ 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