Implement offscreenCanvas.getContext('webgl') on a worker thread

third_party/WebKit/Source/platform/heap/ThreadState.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 223 matching lines @@
     prepareForThreadStateTermination();
 
     ProcessHeap::crossThreadPersistentRegion().prepareForThreadStateTermination(this);
 
     // Do thread local GC's as long as the count of thread local Persistents
     // changes and is above zero.
     int oldCount = -1;
     int currentCount = getPersistentRegion()->numberOfPersistents();
     ASSERT(currentCount >= 0);
     while (currentCount != oldCount) {
+        releaseStaticPersistentNodes();

[pfeldman, 2016/05/06 21:20:40]

What is this about? Could you send it to the heap folks for review?

[xidachen, 2016/05/06 21:41:54]

sof@: Thank you for your CL that clears static persistents.
With your new CL, I guess we don't need this anymore?

[sof, 2016/05/07 05:17:45]

It is still needed, a destructor might still create a thread-local singleton
while shutting down, so we need to be more insistent about releasing those fresh
singletons while cleanly shutting down the worker. But as #32 suggested, this
particular change belongs in a separate CL -- I can take care of that.

The other issue is that the release itself wasn't comprehensive enough for these
persistent collection objects, so we'll need to fix that as well.

(We do not have any other ThreadSpecific<>s over persistent collections in the
codebase.)

         ThreadHeap::collectGarbageForTerminatingThread(this);
         oldCount = currentCount;
         currentCount = getPersistentRegion()->numberOfPersistents();
     }
     // We should not have any persistents left when getting to this point,
     // if we have it is probably a bug so adding a debug ASSERT to catch this.
     ASSERT(!currentCount);
     // All of pre-finalizers should be consumed.
     ASSERT(m_orderedPreFinalizers.isEmpty());
     RELEASE_ASSERT(gcState() == NoGCScheduled);
@@ skipping 1266 matching lines @@
     threadDump->addScalar("dead_count", "objects", totalDeadCount);
     threadDump->addScalar("live_size", "bytes", totalLiveSize);
     threadDump->addScalar("dead_size", "bytes", totalDeadSize);
 
     WebMemoryAllocatorDump* heapsDump = BlinkGCMemoryDumpProvider::instance()->createMemoryAllocatorDumpForCurrentGC(heapsDumpName);
     WebMemoryAllocatorDump* classesDump = BlinkGCMemoryDumpProvider::instance()->createMemoryAllocatorDumpForCurrentGC(classesDumpName);
     BlinkGCMemoryDumpProvider::instance()->currentProcessMemoryDump()->addOwnershipEdge(classesDump->guid(), heapsDump->guid());
 }
 
 } // namespace blink