Oilpan: Ensure that classes with virtual trace methods always have vtables for their left-most base…

Source/modules/indexeddb/IndexedDBClient.h

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 20 matching lines @@
 #include "platform/heap/Handle.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class ExecutionContext;
 
 class IndexedDBClient : public GarbageCollected<IndexedDBClient> {
 public:
     static IndexedDBClient* create();
-    void trace(Visitor*) { }
+    virtual void trace(Visitor*) { }
 
     virtual bool allowIndexedDB(ExecutionContext*, const String& name) = 0;
 };
 
 typedef IndexedDBClient* CreateIndexedDBClient();
 
 void setIndexedDBClientCreateFunction(CreateIndexedDBClient);
 
 } // namespace blink
 
 #endif // IndexedDBClient_h