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

src/isolate.h

 // 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 269 matching lines @@
   // the external callback we're currently in
   ExternalCallbackScope* external_callback_scope_;
   StateTag current_vm_state_;
 
   // Generated code scratch locations.
   int32_t formal_count_;
 
   // Call back function to report unsafe JS accesses.
   v8::FailedAccessCheckCallback failed_access_check_callback_;
 
+  // Call back function to get total physical memory of the platform.
+  v8::TotalPhysicalMemoryCallback total_physical_memory_callback_;
+
   // Head of the list of live LookupResults.
   LookupResult* top_lookup_result_;
 
   // Whether out of memory exceptions should be ignored.
   bool ignore_out_of_memory_;
 
  private:
   void InitializeInternal();
 
   Address try_catch_handler_address_;
@@ skipping 466 matching lines @@
   bool MayNamedAccess(JSObject* receiver,
                       Object* key,
                       v8::AccessType type);
   bool MayIndexedAccess(JSObject* receiver,
                         uint32_t index,
                         v8::AccessType type);
 
   void SetFailedAccessCheckCallback(v8::FailedAccessCheckCallback callback);
   void ReportFailedAccessCheck(JSObject* receiver, v8::AccessType type);
 
+  void SetTotalPhysicalMemoryCallback(v8::TotalPhysicalMemoryCallback callback);
+
   // Exception throwing support. The caller should use the result
   // of Throw() as its return value.
   Failure* Throw(Object* exception, MessageLocation* location = NULL);
   // Re-throw an exception.  This involves no error reporting since
   // error reporting was handled when the exception was thrown
   // originally.
   Failure* ReThrow(MaybeObject* exception);
   void ScheduleThrow(Object* exception);
   // Re-set pending message, script and positions reported to the TryCatch
   // back to the TLS for re-use when rethrowing.
@@ skipping 716 matching lines @@
 
 // Mark the native context with out of memory.
 inline void Context::mark_out_of_memory() {
   native_context()->set_out_of_memory(GetIsolate()->heap()->true_value());
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ISOLATE_H_