Explicit notification and removal of lifecycle observers.

Source/core/workers/WorkerThread.cpp

Index: Source/core/workers/WorkerThread.cpp
diff --git a/Source/core/workers/WorkerThread.cpp b/Source/core/workers/WorkerThread.cpp
index c60511544ab3c579e55ce404dcde5ef77705a1b8..2fcd2ff52d892a26a7b8b8027ec4fbb94264c255 100644
--- a/Source/core/workers/WorkerThread.cpp
+++ b/Source/core/workers/WorkerThread.cpp
@@ -135,18 +135,21 @@ void WorkerThread::workerThread()
 
     ThreadIdentifier threadID = m_threadID;
 
+#if !ENABLE(OILPAN)
+    ASSERT(m_workerGlobalScope->hasOneRef());
+#endif
     // The below assignment will destroy the context, which will in turn notify messaging proxy.

[Mads Ager (chromium), 2014/03/17 08:20:52]

This comment should be updated now that the notification is explicit below.

     // We cannot let any objects survive past thread exit, because no other thread will run GC or otherwise destroy them.
     // If Oilpan is enabled, we detach of the context/global scope, with the final heap cleanup below sweeping it out.
-#if ENABLE(OILPAN)
     m_workerGlobalScope->dispose();
-#else
-    ASSERT(m_workerGlobalScope->hasOneRef());
-#endif
     m_workerGlobalScope = nullptr;
 
     ThreadState::detach();
 
+    // Notify the proxy that WorkerGlobalScope has now been garbage collected and destructed.
+    // This can free this thread object, hence it must not be touched afterwards.
+    workerReportingProxy().workerGlobalScopeDestroyed();
+
     // Clean up PlatformThreadData before WTF::WTFThreadData goes away!
     PlatformThreadData::current().destroy();