Lend LSan a hand and clear out singleton static persistents first.

third_party/WebKit/Source/platform/heap/PersistentNode.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PersistentNode_h
 #define PersistentNode_h
 
 #include "platform/PlatformExport.h"
 #include "platform/heap/ThreadState.h"
 #include "wtf/Allocator.h"
@@ skipping 126 matching lines @@
     m_freeListHead = persistentNode;
 #if DCHECK_IS_ON()
     --m_persistentCount;
 #endif
   }
 
   static bool shouldTracePersistentNode(Visitor*, PersistentNode*) {
     return true;
   }
 
+#if defined(LEAK_SANITIZER)
+  void clearPersistentNode(PersistentNode*,
+                           ThreadState::PersistentClearCallback);
+#endif
   void releasePersistentNode(PersistentNode*,
                              ThreadState::PersistentClearCallback);
   using ShouldTraceCallback = bool (*)(Visitor*, PersistentNode*);
   void tracePersistentNodes(
       Visitor*,
       ShouldTraceCallback = PersistentRegion::shouldTracePersistentNode);
   int numberOfPersistents();
 
  private:
   friend CrossThreadPersistentRegion;
@@ skipping 88 matching lines @@
   // Recursive as prepareForThreadStateTermination() clears a PersistentNode's
   // associated Persistent<> -- it in turn freeing the PersistentNode. And both
   // CrossThreadPersistentRegion operations need a lock on the region before
   // mutating.
   RecursiveMutex m_mutex;
 };
 
 }  // namespace blink
 
 #endif