Two simple profiler changes: 1) log sampling rate, 2) check current state before pausing & resuming.

src/log.h

Index: src/log.h
diff --git a/src/log.h b/src/log.h
index c845feec1f9391763a663888d9750b480ab75c20..10d88330ee18cd10862747c5a0ddf48eedac423b 100644
--- a/src/log.h
+++ b/src/log.h
@@ -220,6 +220,12 @@ class Logger {
 
  private:
 
+  // Profiler's sampling interval (in milliseconds).
+  static const int kSamplingIntervalMs = 1;
+
+  // Emits the profiler's first message.
+  static void ProfilerBeginEvent();
+
   // Emits the source code of a regexp. Used by regexp events.
   static void LogRegExpSource(Handle<JSRegExp> regexp);