Add tasks to zones.

sdk/lib/async/timer.dart

Index: sdk/lib/async/timer.dart
diff --git a/sdk/lib/async/timer.dart b/sdk/lib/async/timer.dart
index fafe65228db5060519b0498e950edbd4347e6fe2..70273e449d533fa6553b1ce194139fb5d9aec7c3 100644
--- a/sdk/lib/async/timer.dart
+++ b/sdk/lib/async/timer.dart
@@ -47,10 +47,17 @@ abstract class Timer {
     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 Timer._createTimer(duration, callback);
     }
-    return Zone.current.createTimer(
-        duration, Zone.current.bindCallback(callback, runGuarded: true));
+    return Zone.current.createTimer(duration, callback);
+  }
+
+  factory Timer._task(Zone zone, Duration duration, void callback()) {
+    SingleShotTimerTaskSpecification specification =
+        new SingleShotTimerTaskSpecification(duration, callback);
+    Object task =
+        Zone.current.createTask(specification, _createSingleShotTimerTask);
+    return new _TimerTaskWrapper(task);
   }
 
   /**
@@ -70,14 +77,67 @@ abstract class Timer {
    * scheduled for - even if the actual callback was delayed.
    */
   factory Timer.periodic(Duration duration,
-                         void callback(Timer timer)) {
+      void callback(Timer timer)) {
     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 Timer._createPeriodicTimer(duration, callback);
     }
-    return Zone.current.createPeriodicTimer(
-        duration, Zone.current.bindUnaryCallback(callback, runGuarded: true));
+    PeriodicTimerTaskSpecification specification =
+        new PeriodicTimerTaskSpecification(duration, callback);
+    Object task =
+        Zone.current.createTask(specification, _createPeriodicTimerTask);
+    return new _TimerTaskWrapper(task);
+  }
+
+  factory Timer._periodicTask(Zone zone, Duration duration,
+      void callback(Timer timer)) {
+    PeriodicTimerTaskSpecification specification =
+        new PeriodicTimerTaskSpecification(duration, callback);
+    Object task =
+        Zone.current.createTask(specification, _createPeriodicTimerTask);
+    return new _TimerTaskWrapper(task);
+  }
+
+  static TimerTask _createSingleShotTimerTask(
+      SingleShotTimerTaskSpecification specification, Zone zone) {
+    ZoneCallback registeredCallback = identical(_ROOT_ZONE, zone)
+        ? specification.callback
+        : zone.registerCallback(specification.callback);
+
+    TimerTask timerTask;
+
+    Timer timer = Timer._createTimer(specification.duration, () {
+      timerTask.zone.runTask(timerTask, null, _runSingleShotCallback);
+    });
+
+    timerTask = new SingleShotTimerTask(timer, registeredCallback, zone);
+    return timerTask;
+  }
+
+  static void _runSingleShotCallback(SingleShotTimerTask timerTask, Object _) {
+    timerTask.callback();
+  }
+
+  static TimerTask _createPeriodicTimerTask(
+      PeriodicTimerTaskSpecification specification, Zone zone) {
+    ZoneUnaryCallback registeredCallback = identical(_ROOT_ZONE, zone)
+        ? specification.callback
+        : zone.registerUnaryCallback(specification.callback);
+
+    TimerTask timerTask;
+
+    Timer timer = Timer._createPeriodicTimer(specification.duration, (Timer _) {
+      timerTask.zone.runTask(timerTask, null, _runPeriodicCallback);
+    });
+
+    timerTask = new PeriodicTimerTask(timer, registeredCallback, zone);
+    return timerTask;
+  }
+
+  static void _runPeriodicCallback(PeriodicTimerTask timerTask, Object _) {
+    // TODO(floitsch): cache the TimerWrapper?
+    timerTask.callback(new _TimerTaskWrapper(timerTask));
   }
 
   /**