Implement resource-saving mode of Profiler.

src/log.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 212 matching lines @@
   static void LogRegExpSource(Handle<JSRegExp> regexp);
 
   // Emits a profiler tick event. Used by the profiler thread.
   static void TickEvent(TickSample* sample, bool overflow);
 
   static void ApiEvent(const char* name, ...);
 
   // Logs a StringEvent regardless of whether FLAG_log is true.
   static void UncheckedStringEvent(const char* name, const char* value);
 
+  // Returns whether profiler's sampler is active.
+  static bool IsProfilerSamplerActive();
+
   // The sampler used by the profiler and the sliding state window.
   static Ticker* ticker_;
 
   // When the statistical profile is active, profiler_
   // points to a Profiler, that handles collection
   // of samples.
   static Profiler* profiler_;
 
   // A stack of VM states.
   static VMState* current_state_;
 
   // Singleton bottom or default vm state.
   static VMState bottom_state_;
 
   // SlidingStateWindow instance keeping a sliding window of the most
   // recent VM states.
   static SlidingStateWindow* sliding_state_window_;
 
   // Internal implementation classes with access to
   // private members.
   friend class EventLog;
   friend class TimeLog;
   friend class Profiler;
   friend class SlidingStateWindow;
   friend class VMState;
+
+  friend class LoggerTestHelper;
 #else
   static bool is_enabled() { return false; }
 #endif
 };
 
 
 // Class that extracts stack trace, used for profiling.
 class StackTracer BASE_EMBEDDED {
  public:
   explicit StackTracer(uintptr_t low_stack_bound)
       : low_stack_bound_(low_stack_bound) { }
   void Trace(TickSample* sample);
  private:
 
   uintptr_t low_stack_bound_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_LOG_H_