[simulator] Make reference redirection thread-safe.

src/isolate.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_ISOLATE_H_
 #define V8_ISOLATE_H_
 
 #include <memory>
 #include <queue>
 
@@ skipping 1232 matching lines @@
   void IsolateInForegroundNotification();
 
   void IsolateInBackgroundNotification();
 
   bool IsIsolateInBackground() { return is_isolate_in_background_; }
 
   PRINTF_FORMAT(2, 3) void PrintWithTimestamp(const char* format, ...);
 
 #ifdef USE_SIMULATOR
   base::Mutex* simulator_i_cache_mutex() { return &simulator_i_cache_mutex_; }
+  base::Mutex* simulator_redirection_mutex() {
+    return &simulator_redirection_mutex_;
+  }
 #endif
 
   void set_allow_atomics_wait(bool set) { allow_atomics_wait_ = set; }
   bool allow_atomics_wait() { return allow_atomics_wait_; }
 
   // List of native heap values allocated by the runtime as part of its
   // implementation that must be freed at isolate deinit.
   class ManagedObjectFinalizer final {
    public:
     typedef void (*Deleter)(void*);
@@ skipping 300 matching lines @@
 
   CancelableTaskManager* cancelable_task_manager_;
 
   debug::ConsoleDelegate* console_delegate_ = nullptr;
 
   v8::Isolate::AbortOnUncaughtExceptionCallback
       abort_on_uncaught_exception_callback_;
 
 #ifdef USE_SIMULATOR
   base::Mutex simulator_i_cache_mutex_;
+  base::Mutex simulator_redirection_mutex_;
 #endif
 
   bool allow_atomics_wait_;
 
   ManagedObjectFinalizer managed_object_finalizers_list_;
 
   size_t total_regexp_code_generated_;
 
   int wait_count_ = 0;
 
@@ skipping 227 matching lines @@
 
   EmbeddedVector<char, 128> filename_;
   FILE* file_;
   int scope_depth_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_ISOLATE_H_