Expose Zones.

sdk/lib/async/timer.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.async;
 
 /**
  * A count-down timer that can be configured to fire once or repeatedly.
  *
  * The timer counts down from the specified duration to 0.
@@ skipping 14 matching lines @@
  *       var duration = milliseconds == null ? TIMEOUT : ms * milliseconds;
  *       return new Timer(duration, handleTimeout);
  *     }
  *     ...
  *     void handleTimeout() {  // callback function
  *       ...
  *     }
  *
  * Note: If Dart code using Timer is compiled to JavaScript, the finest
  * granularity available in the browser is 4 milliseconds.
- * 
+ *
  * See [Stopwatch] for measuring elapsed time.
  */
 abstract class Timer {
 
   /**
    * Creates a new timer.
    *
    * The [callback] function is invoked after the given [duration].
    *
    */
   factory Timer(Duration duration, void callback()) {
-    return _Zone.current.createTimer(duration, callback);
+    if (Zone.current == Zone.ROOT) {
+      // No need to bind the callback. We know that the root's timer will
+      // be invoked in the root zone.
+      return Zone.current.createTimer(duration, callback);
+    }
+    return Zone.current.createTimer(
+        duration, Zone.current.bindCallback(callback, runGuarded: true));
   }
 
   /**
    * Creates a new repeating timer.
    *
    * The [callback] is invoked repeatedly with [duration] intervals until
    * canceled with the [cancel] function.
    */
   factory Timer.periodic(Duration duration,
                                   void callback(Timer timer)) {
-    return _Zone.current.createPeriodicTimer(duration, callback);
+    if (Zone.current == Zone.ROOT) {
+      // No need to bind the callback. We know that the root's timer will
+      // be invoked in the root zone.
+      return Zone.current.createPeriodicTimer(duration, callback);
+    }
+    return Zone.current.createPeriodicTimer(
+        duration, Zone.current.bindUnaryCallback(callback, runGuarded: true));
   }
 
   /**
    * Runs the given [callback] asynchronously as soon as possible.
    *
    * This function is equivalent to `new Timer(Duration.ZERO, callback)`.
    */
   static void run(void callback()) {
     new Timer(Duration.ZERO, callback);
   }
@@ skipping 10 matching lines @@
    * and the timer has not been canceled.
    *
    * A periodic timer is active if it has not been canceled.
    */
   bool get isActive;
 }
 
 external Timer _createTimer(Duration duration, void callback());
 external Timer _createPeriodicTimer(Duration duration,
                                     void callback(Timer timer));