Also time external callbacks from generated code.

src/log.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 262 matching lines @@
                           uintptr_t start,
                           uintptr_t end);
   void SharedLibraryEvent(const wchar_t* library_path,
                           uintptr_t start,
                           uintptr_t end);
 
   // ==== Events logged by --log-timer-events. ====
   void TimerEvent(const char* name, int64_t start, int64_t end);
   void ExternalSwitch(StateTag old_tag, StateTag new_tag);
 
+  static void EnterExternal();
+  static void LeaveExternal();
+
   class TimerEventScope {
    public:
     TimerEventScope(Isolate* isolate, const char* name)
         : isolate_(isolate), name_(name), start_(0) {
       if (FLAG_log_timer_events) start_ = OS::Ticks();
     }
 
     ~TimerEventScope() {
       if (FLAG_log_timer_events) LogTimerEvent();
     }
@@ skipping 229 matching lines @@
 // Class that extracts stack trace, used for profiling.
 class StackTracer : public AllStatic {
  public:
   static void Trace(Isolate* isolate, TickSample* sample);
 };
 
 } }  // namespace v8::internal
 
 
 #endif  // V8_LOG_H_