Add --timing

runtime/vm/thread_registry.h

Index: runtime/vm/thread_registry.h
diff --git a/runtime/vm/thread_registry.h b/runtime/vm/thread_registry.h
index cb106269c2a526fef36febf0a3810e9c6ab90aa0..01f52a356ef3eea212075a2023e040b2330f5825 100644
--- a/runtime/vm/thread_registry.h
+++ b/runtime/vm/thread_registry.h
@@ -142,6 +142,8 @@ class ThreadRegistry {
 
   void PruneThread(Thread* thread);
 
+  void CloseAllTimelineBlocks();
+
   struct Entry {
     // NOTE: |thread| is deleted automatically when the thread exits.
     // In other words, it is not safe to dereference |thread| unless you are on
@@ -182,6 +184,11 @@ class ThreadRegistry {
     return NULL;
   }
 
+  // Close the timeline block cache inside entry.
+  // NOTE: Lock should be taken before this function is called.
+  // NOTE: Recorder lock should be taken before this function is called.
+  void CloseTimelineBlockLocked(Entry* entry);
+
   // Note: Lock should be taken before this function is called.
   void CheckSafepointLocked();