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

third_party/WebKit/Source/core/html/HTMLPlugInElement.cpp

 /**
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Stefan Schimanski (1Stein@gmx.de)
  * Copyright (C) 2004, 2005, 2006 Apple Computer, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 78 matching lines @@
   DCHECK(plugin_wrapper_.IsEmpty());  // cleared in detachLayoutTree()
   DCHECK(!is_delaying_load_event_);
 }
 
 DEFINE_TRACE(HTMLPlugInElement) {
   visitor->Trace(image_loader_);
   visitor->Trace(persisted_plugin_);
   HTMLFrameOwnerElement::Trace(visitor);
 }
 
+bool HTMLPlugInElement::HasPendingActivity() const {
+  return image_loader_ && image_loader_->HasPendingActivity();
+}
+
 void HTMLPlugInElement::SetPersistedPlugin(PluginView* plugin) {
   if (persisted_plugin_ == plugin)
     return;
   if (persisted_plugin_) {
     persisted_plugin_->Hide();
     DisposeFrameOrPluginSoon(persisted_plugin_.Release());
   }
   persisted_plugin_ = plugin;
 }
 
@@ skipping 559 matching lines @@
 
 void HTMLPlugInElement::LazyReattachIfNeeded() {
   if (!UseFallbackContent() && NeedsPluginUpdate() && GetLayoutObject() &&
       !IsImageType()) {
     LazyReattachIfAttached();
     SetPersistedPlugin(nullptr);
   }
 }
 
 }  // namespace blink