Provide a way for iterating through all external strings referenced from the JS heap

include/v8.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
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   char** raw_data;
 };
 
 
 /**
  * EntropySource is used as a callback function when v8 needs a source
  * of entropy.
  */
 typedef bool (*EntropySource)(unsigned char* buffer, size_t length);
 
+
+/**
+ * Interface for iterating though all external resources in the heap.
+ */
+class V8EXPORT ExternalResourceVisitor {
+ public:
+  virtual ~ExternalResourceVisitor() {}
+  virtual void VisitExternalString(Handle<String> string) {}
+};
+
+
 /**
  * Container class for static utility functions.
  */
 class V8EXPORT V8 {
  public:
   /** Set the callback to invoke in case of fatal errors. */
   static void SetFatalErrorHandler(FatalErrorCallback that);
 
   /**
    * Set the callback to invoke to check if code generation from
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    * to use if the process needs the resources taken up by v8.
    */
   static bool Dispose();
 
   /**
    * Get statistics about the heap memory usage.
    */
   static void GetHeapStatistics(HeapStatistics* heap_statistics);
 
   /**
+   * Iterates through all external resources referenced from current isolate
+   * heap.
+   */
+  static void VisitExternalResources(ExternalResourceVisitor* visitor);
+
+  /**
    * Optional notification that the embedder is idle.
    * V8 uses the notification to reduce memory footprint.
    * This call can be used repeatedly if the embedder remains idle.
    * Returns true if the embedder should stop calling IdleNotification
    * until real work has been done.  This indicates that V8 has done
    * as much cleanup as it will be able to do.
    *
    * The hint argument specifies the amount of work to be done in the function
    * on scale from 1 to 1000. There is no guarantee that the actual work will
    * match the hint.
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 }  // namespace v8
 
 
 #undef V8EXPORT
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_