Revert of Simplify the shutdown sequence of Oilpan's heap

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 46272814d0ae337f41e2e2cd977347a4f4c0d74f..01ed8598dd0c01cf5df0c254f59d357df35af818 100644
--- a/third_party/WebKit/Source/platform/heap/ThreadState.cpp
+++ b/third_party/WebKit/Source/platform/heap/ThreadState.cpp
@@ -235,6 +235,19 @@
         attachedThreads().remove(state);
         state->~ThreadState();
     }
+    shutdownHeapIfNecessary();
+}
+
+void ThreadState::shutdownHeapIfNecessary()
+{
+    // We don't need to enter a safe point before acquiring threadAttachMutex
+    // because this thread is already detached.
+
+    MutexLocker locker(threadAttachMutex());
+    // We start shutting down the heap if there is no running thread
+    // and Heap::shutdown() is already called.
+    if (!attachedThreads().size() && Heap::s_shutdownCalled)
+        Heap::doShutdown();
 }
 
 void ThreadState::attach()
@@ -310,6 +323,7 @@
     state->cleanup();
     RELEASE_ASSERT(state->gcState() == ThreadState::NoGCScheduled);
     delete state;
+    shutdownHeapIfNecessary();
 }
 
 void ThreadState::visitPersistentRoots(Visitor* visitor)