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

third_party/WebKit/Source/platform/heap/ThreadState.cpp

Index: third_party/WebKit/Source/platform/heap/ThreadState.cpp
diff --git a/third_party/WebKit/Source/platform/heap/ThreadState.cpp b/third_party/WebKit/Source/platform/heap/ThreadState.cpp
index e1294ec308fb758f3ef5f6e26e3ba3df415c4253..cbf3b3c2f1ba769d4f323380e8480ed79e2a0a0e 100644
--- a/third_party/WebKit/Source/platform/heap/ThreadState.cpp
+++ b/third_party/WebKit/Source/platform/heap/ThreadState.cpp
@@ -241,6 +241,7 @@ void ThreadState::runTerminationGC()
     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();