Revert of Move ThreadableLoader to Oilpan heap (2/3)

third_party/WebKit/Source/modules/notifications/NotificationImageLoader.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/notifications/NotificationImageLoader.h"
 
 #include "core/dom/ExecutionContext.h"
 #include "core/fetch/ResourceLoaderOptions.h"
 #include "platform/Histogram.h"
 #include "platform/image-decoders/ImageDecoder.h"
@@ skipping 47 matching lines @@
 }
 
 void NotificationImageLoader::stop()
 {
     if (m_stopped)
         return;
 
     m_stopped = true;
     if (m_threadableLoader) {
         m_threadableLoader->cancel();
-        m_threadableLoader = nullptr;
+        // WorkerThreadableLoader keeps a Persistent<WorkerGlobalScope> to the
+        // ExecutionContext it received in |create|. Kill it to prevent
+        // reference cycles involving a mix of GC and non-GC types that fail to
+        // clear in ThreadState::cleanup.
+        m_threadableLoader.reset();
     }
 }
 
 void NotificationImageLoader::didReceiveData(const char* data, unsigned length)
 {
     if (!m_data)
         m_data = SharedBuffer::create();
     m_data->append(data, length);
 }
 
@@ skipping 42 matching lines @@
 {
     // If this has been stopped it is not desirable to trigger further work,
     // there is a shutdown of some sort in progress.
     if (m_stopped)
         return;
 
     (*m_imageCallback)(SkBitmap());
 }
 
 } // namespace blink