Reduce CPU usage when no isolates need to be profiled.

runtime/bin/utils.h

Index: runtime/bin/utils.h
diff --git a/runtime/bin/utils.h b/runtime/bin/utils.h
index 60beef1ade10b4a56de41d5b1557d3c63601a87e..7b8818a625bb705c17938d231e195696b48e8007 100644
--- a/runtime/bin/utils.h
+++ b/runtime/bin/utils.h
@@ -89,6 +89,17 @@ class TimerUtils {
   static void Sleep(int64_t millis);
 };
 
+class ProfilerBlocker {

[Anders Johnsen, 2014/05/25 18:36:34]

Stuff like this usually go into dartutils.h.

[Cutch, 2014/05/26 06:59:35]

Done and renamed to ScopedBlockingCall

+ public:
+  ProfilerBlocker() {
+    Dart_BlockProfiler();
+  }
+
+  ~ProfilerBlocker() {
+    Dart_UnblockProfiler();
+  }
+};
+
 }  // namespace bin
 }  // namespace dart