Provide a mechanism for the embedder to set a TotalPhysicalMemory callback function.

src/isolate.cc

 // Copyright 2012 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 84 matching lines @@
   simulator_ = NULL;
 #endif
   js_entry_sp_ = NULL;
   external_callback_scope_ = NULL;
   current_vm_state_ = EXTERNAL;
   try_catch_handler_address_ = NULL;
   context_ = NULL;
   thread_id_ = ThreadId::Invalid();
   external_caught_exception_ = false;
   failed_access_check_callback_ = NULL;
+  total_physical_memory_callback_ = NULL;
   save_context_ = NULL;
   catcher_ = NULL;
   top_lookup_result_ = NULL;
 
   // These members are re-initialized later after deserialization
   // is complete.
   pending_exception_ = NULL;
   has_pending_message_ = false;
   rethrowing_message_ = false;
   pending_message_obj_ = NULL;
@@ skipping 840 matching lines @@
   Handle<Object> data(AccessCheckInfo::cast(data_obj)->data(), this);
   { VMState<EXTERNAL> state(this);
     thread_local_top()->failed_access_check_callback_(
       v8::Utils::ToLocal(receiver_handle),
       type,
       v8::Utils::ToLocal(data));
   }
 }
 
 
+void Isolate::SetTotalPhysicalMemoryCallback(
+      v8::TotalPhysicalMemoryCallback callback) {
+  thread_local_top()->total_physical_memory_callback_ = callback;
+}
+
+
 enum MayAccessDecision {
   YES, NO, UNKNOWN
 };
 
 
 static MayAccessDecision MayAccessPreCheck(Isolate* isolate,
                                            JSObject* receiver,
                                            v8::AccessType type) {
   // During bootstrapping, callback functions are not enabled yet.
   if (isolate->bootstrapper()->IsActive()) return YES;
@@ skipping 1540 matching lines @@
 
 #ifdef DEBUG
 #define ISOLATE_FIELD_OFFSET(type, name, ignored)                       \
 const intptr_t Isolate::name##_debug_offset_ = OFFSET_OF(Isolate, name##_);
 ISOLATE_INIT_LIST(ISOLATE_FIELD_OFFSET)
 ISOLATE_INIT_ARRAY_LIST(ISOLATE_FIELD_OFFSET)
 #undef ISOLATE_FIELD_OFFSET
 #endif
 
 } }  // namespace v8::internal