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

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

Index: third_party/WebKit/Source/core/html/HTMLMediaElement.h
diff --git a/third_party/WebKit/Source/core/html/HTMLMediaElement.h b/third_party/WebKit/Source/core/html/HTMLMediaElement.h
index 563d26bb06722690d391ac68946b168884d883a8..e530558dc279e76b1a9101ec397ba5ecd0ea6e1c 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.h
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.h
@@ -338,6 +338,10 @@ class CORE_EXPORT HTMLMediaElement
   ~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;