V8 Sampling Profiler: Collect V8 sample trace events on Linux and MacOS

content/renderer/devtools/v8_sampling_profiler.h

Index: content/renderer/devtools/v8_sampling_profiler.h
diff --git a/content/renderer/devtools/v8_sampling_profiler.h b/content/renderer/devtools/v8_sampling_profiler.h
index 50cae06a15870161d5c3698df88beead2e7dffc0..346a46c236580bba4a649a76ab9c8a7d371a869d 100644
--- a/content/renderer/devtools/v8_sampling_profiler.h
+++ b/content/renderer/devtools/v8_sampling_profiler.h
@@ -30,9 +30,12 @@ class CONTENT_EXPORT V8SamplingProfiler final
   void WaitSamplingEventForTesting();
 
  private:
+  void StartSamplingThread();
+
   scoped_ptr<base::WaitableEvent> waitable_event_for_testing_;
   scoped_ptr<V8SamplingThread> sampling_thread_;
   scoped_ptr<Sampler> render_thread_sampler_;
+  scoped_refptr<base::MessageLoopProxy> message_loop_proxy_;
 
   DISALLOW_COPY_AND_ASSIGN(V8SamplingProfiler);
 };