Add an API to control the disposal of external string resources...

src/heap.h

 // Copyright 2006-2008 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
@@ skipping 672 matching lines @@
 
   // Utility to invoke the scavenger. This is needed in test code to
   // ensure correct callback for weak global handles.
   static void PerformScavenge();
 
 #ifdef DEBUG
   // Utility used with flag gc-greedy.
   static bool GarbageCollectionGreedyCheck();
 #endif
 
+  static void SetExternalStringDiposeCallback(
+      ExternalStringDiposeCallback callback) {
+    external_string_dispose_callback_ = callback;
+  }
+
   static void AddGCPrologueCallback(
       GCEpilogueCallback callback, GCType gc_type_filter);
   static void RemoveGCPrologueCallback(GCEpilogueCallback callback);
 
   static void AddGCEpilogueCallback(
       GCEpilogueCallback callback, GCType gc_type_filter);
   static void RemoveGCEpilogueCallback(GCEpilogueCallback callback);
 
   static void SetGlobalGCPrologueCallback(GCCallback callback) {
     ASSERT((callback == NULL) ^ (global_gc_prologue_callback_ == NULL));
@@ skipping 428 matching lines @@
   };
 
   static const StringTypeTable string_type_table[];
   static const ConstantSymbolTable constant_symbol_table[];
   static const StructTable struct_table[];
 
   // The special hidden symbol which is an empty string, but does not match
   // any string when looked up in properties.
   static String* hidden_symbol_;
 
+  static ExternalStringDiposeCallback
+       external_string_dispose_callback_;
+
   // GC callback function, called before and after mark-compact GC.
   // Allocations in the callback function are disallowed.
   struct GCPrologueCallbackPair {
     GCPrologueCallbackPair(GCPrologueCallback callback, GCType gc_type)
         : callback(callback), gc_type(gc_type) {
     }
     bool operator==(const GCPrologueCallbackPair& pair) const {
       return pair.callback == callback;
     }
     GCPrologueCallback callback;
@@ skipping 777 matching lines @@
 
   // To speed up scavenge collections new space string are kept
   // separate from old space strings.
   static List<Object*> new_space_strings_;
   static List<Object*> old_space_strings_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_