Only call OS::GetCurrentThreadCPUMicros when a TimelineDurationScope is enabled

runtime/vm/timeline.cc

Index: runtime/vm/timeline.cc
diff --git a/runtime/vm/timeline.cc b/runtime/vm/timeline.cc
index 54735a033f58610559c46398fb94394358fb0200..4284ff28ff87236862c0ab56fcd1173d4370b08d 100644
--- a/runtime/vm/timeline.cc
+++ b/runtime/vm/timeline.cc
@@ -887,8 +887,10 @@ TimelineDurationScope::TimelineDurationScope(TimelineStream* stream,
   if (!FLAG_support_timeline) {
     return;
   }
-  timestamp_ = OS::GetCurrentMonotonicMicros();
-  thread_timestamp_ = OS::GetCurrentThreadCPUMicros();
+  if (enabled()) {
+    timestamp_ = OS::GetCurrentMonotonicMicros();
+    thread_timestamp_ = OS::GetCurrentThreadCPUMicros();
+  }
 }
 
 
@@ -899,8 +901,10 @@ TimelineDurationScope::TimelineDurationScope(Thread* thread,
   if (!FLAG_support_timeline) {

[Ivan Posva, 2016/05/12 18:47:46]

if (!FLAG_support_timeline || !enabled()) {

[Cutch, 2016/05/12 20:06:22]

Done.

     return;
   }
-  timestamp_ = OS::GetCurrentMonotonicMicros();
-  thread_timestamp_ = OS::GetCurrentThreadCPUMicros();
+  if (enabled()) {
+    timestamp_ = OS::GetCurrentMonotonicMicros();
+    thread_timestamp_ = OS::GetCurrentThreadCPUMicros();
+  }
 }