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

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

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013 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
@@ skipping 320 matching lines @@
 
   const AutoplayPolicy& GetAutoplayPolicy() const { return *autoplay_policy_; }
 
   WebMediaPlayer::LoadType GetLoadType() const;
 
  protected:
   HTMLMediaElement(const QualifiedName&, Document&);
   ~HTMLMediaElement() override;
   void Dispose();
 
+  // Returns true if HasPendingActivity() should be true for
+  // subclass-specific reasons.
+  virtual bool HasPendingActivityInternal() const { return false; }

[kouhei (in TOK), 2017/05/29 05:27:34]

Why is this needed?
HTMLVideoElement inherits from HTMLMediaElement so sounds like it could directly
use HasPendingActivity

[hiroshige, 2017/05/29 10:37:00]

I did so in Patch Set 2 but it didn't work, perhaps because
T::HasPendingActivity is called directly for ActiveScriptWrappable<T> via
https://codesearch.chromium.org/chromium/src/third_party/WebKit/Source/platfo...,
which doesn't consider overrides.

[hiroshige, 2017/05/30 08:57:06]

According to offline discussion with kouhei@, I modify ActiveScriptWrappable to
allow HasPendingActivity() overriding
(https://codereview.chromium.org/2907173002) and remove
HasPendingActivityInternal() hack in this CL in Patch Set 4.

+
   void ParseAttribute(const AttributeModificationParams&) override;
   void FinishParsingChildren() final;
   bool IsURLAttribute(const Attribute&) const override;
   void AttachLayoutTree(const AttachContext& = AttachContext()) override;
 
   InsertionNotificationRequest InsertedInto(ContainerNode*) override;
   void RemovedFrom(ContainerNode*) override;
 
   void DidMoveToNewDocument(Document& old_document) override;
   virtual KURL PosterImageURL() const { return KURL(); }
@@ skipping 389 matching lines @@
 
 inline bool IsHTMLMediaElement(const HTMLElement& element) {
   return isHTMLAudioElement(element) || isHTMLVideoElement(element);
 }
 
 DEFINE_HTMLELEMENT_TYPE_CASTS_WITH_FUNCTION(HTMLMediaElement);
 
 }  // namespace blink
 
 #endif  // HTMLMediaElement_h