Remove the lifetime hack in ImageLoader where it keeps its assoc element alive

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

 /*
  * Copyright (C) 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 36 matching lines @@
 
 class CORE_EXPORT HTMLVideoElement final : public HTMLMediaElement,
                                            public CanvasImageSource,
                                            public ImageBitmapSource {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
   static HTMLVideoElement* Create(Document&);
   DECLARE_VIRTUAL_TRACE();
 
+  bool HasPendingActivity() const final;
+
   enum class MediaRemotingStatus { kNotStarted, kStarted, kDisabled };
 
   // Node override.
   Node::InsertionNotificationRequest InsertedInto(ContainerNode*) override;
   void RemovedFrom(ContainerNode*) override;
 
   unsigned videoWidth() const;
   unsigned videoHeight() const;
 
   // Fullscreen
@@ skipping 112 matching lines @@
   Member<MediaRemotingInterstitial> remoting_interstitial_;
 
   AtomicString default_poster_url_;
 
   bool is_persistent_ = false;
 };
 
 }  // namespace blink
 
 #endif  // HTMLVideoElement_h