ActiveScriptWrappable: GC wrappers in detached ExecutionContexts.

third_party/WebKit/Source/modules/mediasource/SourceBuffer.cpp

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 98 matching lines @@
     GenericEventQueue* asyncEventQueue) {
   SourceBuffer* sourceBuffer =
       new SourceBuffer(std::move(webSourceBuffer), source, asyncEventQueue);
   sourceBuffer->suspendIfNeeded();
   return sourceBuffer;
 }
 
 SourceBuffer::SourceBuffer(std::unique_ptr<WebSourceBuffer> webSourceBuffer,
                            MediaSource* source,
                            GenericEventQueue* asyncEventQueue)
-    : ActiveScriptWrappable(this),
+    : ActiveScriptWrappable<SourceBuffer>(this),
       SuspendableObject(source->getExecutionContext()),
       m_webSourceBuffer(std::move(webSourceBuffer)),
       m_source(source),
       m_trackDefaults(TrackDefaultList::create()),
       m_asyncEventQueue(asyncEventQueue),
       m_mode(segmentsKeyword()),
       m_updating(false),
       m_timestampOffset(0),
       m_appendWindowStart(0),
       m_appendWindowEnd(std::numeric_limits<double>::infinity()),
@@ skipping 1175 matching lines @@
   visitor->trace(m_asyncEventQueue);
   visitor->trace(m_appendBufferAsyncPartRunner);
   visitor->trace(m_removeAsyncPartRunner);
   visitor->trace(m_audioTracks);
   visitor->trace(m_videoTracks);
   EventTargetWithInlineData::trace(visitor);
   SuspendableObject::trace(visitor);
 }
 
 }  // namespace blink