Fix shutdown race when running Dart on the message loop

tonic/dart_message_handler.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef TONIC_DART_MESSAGE_HANDLER_H_
 #define TONIC_DART_MESSAGE_HANDLER_H_
 
 #include "base/callback.h"
 #include "base/message_loop/message_loop.h"
 #include "dart/runtime/include/dart_api.h"
 
 namespace tonic {
 class DartState;
 
 class DartMessageHandler {
  public:
   DartMessageHandler();
   ~DartMessageHandler();
 
   // Messages for the current isolate will be scheduled on |runner|.
   void Initialize(const scoped_refptr<base::SingleThreadTaskRunner>& runner);
 
+  // Request the message loop to quit when isolate exits? Default is true.
+  void set_quit_message_loop_when_isolate_exits(
+      bool quit_message_loop_when_isolate_exits) {
+    quit_message_loop_when_isolate_exits_ =
+        quit_message_loop_when_isolate_exits;
+  }
+
+  bool quit_message_loop_when_isolate_exits() const {
+    return quit_message_loop_when_isolate_exits_;
+  }
+
+  // Did the isolate exit?
+  bool isolate_exited() const {
+    return isolate_exited_;
+  }
+
+  // Did the isolate have an uncaught exception error?
+  bool isolate_had_uncaught_exception_error() const {
+    return isolate_had_uncaught_exception_error_;
+  }
+
  protected:
   // Called from an unknown thread for each message.
   void OnMessage(DartState* dart_state);
   // By default, called on the task runner's thread for each message.
   void OnHandleMessage(DartState* dart_state);
 
   scoped_refptr<base::SingleThreadTaskRunner> task_runner() const {
     return task_runner_;
   }
 
   bool handled_first_message() const {
     return handled_first_message_;
   }
 
   void set_handled_first_message(bool handled_first_message) {
     handled_first_message_ = handled_first_message;
   }
 
   bool handled_first_message_;
+  bool quit_message_loop_when_isolate_exits_;
+  bool isolate_exited_;
+  bool isolate_had_uncaught_exception_error_;
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
  private:
   static void HandleMessage(base::WeakPtr<DartState> dart_state);
   static void MessageNotifyCallback(Dart_Isolate dest_isolate);
 };
 
 }  // namespace tonic
 
 #endif  // TONIC_DART_MESSAGE_HANDLER_H_