Add a CustomSchemeHandler runtime flag to remove ENABLE(CUSTOM_SCHEME_HANDLER)

Source/web/ChromeClientImpl.h

 /*
  * 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 200 matching lines @@
 
     WebCore::PagePopupDriver* m_pagePopupDriver;
 };
 
 class NavigatorContentUtilsClientImpl : public WebCore::NavigatorContentUtilsClient {
 public:
     static PassOwnPtr<NavigatorContentUtilsClientImpl> create(WebViewImpl*);
     ~NavigatorContentUtilsClientImpl() { }
 
     virtual void registerProtocolHandler(const String& scheme, const String& baseURL, const String& url, const String& title) OVERRIDE;
+    virtual CustomHandlersState isProtocolHandlerRegistered(const String& scheme, const String& baseURL, const String& url) OVERRIDE;
+    virtual void unregisterProtocolHandler(const String& scheme, const String& baseURL, const String& url) OVERRIDE;
 
 private:
     explicit NavigatorContentUtilsClientImpl(WebViewImpl*);
 
     WebViewImpl* m_webView;
 };
 
 DEFINE_TYPE_CASTS(ChromeClientImpl, WebCore::ChromeClient, client, client->isChromeClientImpl(), client.isChromeClientImpl());
 
 } // namespace blink
 
 #endif