Oilpan: Add ThreadState cleanup callbacks for static thread-specific persistent.

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 873baa3c94e48d340e093e52178b17933042dc4d..b26c3ea8315a6962b8d9be03a8cbc9e3d4ad4b60 100644
--- a/third_party/WebKit/Source/platform/heap/ThreadState.cpp
+++ b/third_party/WebKit/Source/platform/heap/ThreadState.cpp
@@ -292,6 +292,12 @@ void ThreadState::cleanup()
         // pointers into the heap owned by this thread.
         m_isTerminating = true;
 
+        // Invoke the cleanup hooks. This gives an opportunity to release any
+        // persistent handles that may exist, e.g. in thread-specific static
+        // locals.
+        for (const OwnPtr<SameThreadClosure>& hook : m_cleanupHooks)
+            (*hook)();
+
         // Set the terminate flag on all heap pages of this thread. This is used to
         // ensure we don't trace pages on other threads that are not part of the
         // thread local GC.
@@ -1359,6 +1365,13 @@ void ThreadState::addInterruptor(PassOwnPtr<BlinkGCInterruptor> interruptor)
     }
 }
 
+void ThreadState::registerCleanupHook(PassOwnPtr<SameThreadClosure> hook)
+{
+    ASSERT(checkThread());
+    ASSERT(!isTerminating());
+    m_cleanupHooks.append(hook);
+}
+
 #if defined(LEAK_SANITIZER)
 void ThreadState::registerStaticPersistentNode(PersistentNode* node)
 {