Remove MediaQueryList listener from removed HTMLSourceElement.

third_party/WebKit/Source/core/html/HTMLPictureElement.h

 // Copyright 2014 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 HTMLPictureElement_h
 #define HTMLPictureElement_h
 
 #include "core/html/HTMLElement.h"
 
 namespace blink {
 
 class HTMLPictureElement final : public HTMLElement {
     DEFINE_WRAPPERTYPEINFO();
 public:
     DECLARE_NODE_FACTORY(HTMLPictureElement);
 
     void sourceOrMediaChanged();
+    void removeListenerFromSourceChildren();
+    void addListenerToSourceChildren();
 
 protected:
     explicit HTMLPictureElement(Document&);
 
 private:
     InsertionNotificationRequest insertedInto(ContainerNode*) override;
 };
 
 } // namespace blink
 
 #endif // HTMLPictureElement_h