- Add assertions in MutexLocker/MonitorLocker to ensure that the code enclosed

runtime/vm/message_handler.h

Index: runtime/vm/message_handler.h
diff --git a/runtime/vm/message_handler.h b/runtime/vm/message_handler.h
index 47dfa99073a0e3dd39d6266954a58b127ebd7163..6f0132899fe683ccb7aaa080a2e7825b2e4f38c3 100644
--- a/runtime/vm/message_handler.h
+++ b/runtime/vm/message_handler.h
@@ -12,6 +12,9 @@
 
 namespace dart {
 
+// Forward declarations.
+class MonitorLocker;
+
 // A MessageHandler is an entity capable of accepting messages.
 class MessageHandler {
  protected:
@@ -225,7 +228,8 @@ class MessageHandler {
   void ClearOOBQueue();
 
   // Handles any pending messages.
-  MessageStatus HandleMessages(bool allow_normal_messages,
+  MessageStatus HandleMessages(MonitorLocker* ml,
+                               bool allow_normal_messages,
                                bool allow_multiple_normal_messages);
 
   Monitor monitor_;  // Protects all fields in MessageHandler.