Make TimelineEventBlocks reclaimable

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index 685e457309e103c72e593b692c8b3003ee86495b..e3164bc07ab6f4e3b13ab946877840f0ebdf7272 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -1515,8 +1515,8 @@ void Isolate::LowLevelShutdown() {
   // Dump all accumulated timer data for the isolate.
   timer_list_.ReportTimers();
 
-  // Before analyzing the isolate's timeline blocks- close all of them.
-  CloseAllTimelineBlocks();
+  // Before analyzing the isolate's timeline blocks- reclaim all cached blocks.
+  ReclaimTimelineBlocks();
 
   // Dump all timing data for the isolate.
   if (FLAG_timing) {
@@ -1616,14 +1616,12 @@ void Isolate::Shutdown() {
 }
 
 
-void Isolate::CloseAllTimelineBlocks() {
-  // Close all blocks
-  thread_registry_->CloseAllTimelineBlocks();
+void Isolate::ReclaimTimelineBlocks() {
   TimelineEventRecorder* recorder = Timeline::recorder();
-  if (recorder != NULL) {
-    MutexLocker ml(&recorder->lock_);
-    Thread::Current()->CloseTimelineBlock();
+  if (recorder == NULL) {
+    return;
   }
+  thread_registry_->ReclaimTimelineBlocks();
 }