Add a simple inksplash example

sky/sdk/lib/framework/scheduler.dart

+// Copyright 2015 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.
+
+import 'dart:async';
+import 'dart:sky' as sky;
+
+typedef void Callback(double timeStamp);
+
+bool _haveScheduledVisualUpdate = false;
+int _nextCallbackId = 1;
+
+final List<Callback> _persistentCallbacks = new List<Callback>();
+Map<int, Callback> _transientCallbacks = new Map<int, Callback>();
+
+void _beginFrame(double timeStamp) {
+  _haveScheduledVisualUpdate = false;
+
+  Map<int, Callback> callbacks = _transientCallbacks;
+  _transientCallbacks = new Map<int, Callback>();
+
+  callbacks.forEach((id, callback) {
+    callback(timeStamp);
+  });
+
+  for (Callback callback in _persistentCallbacks)
+    callback(timeStamp);
+}
+
+void init() {
+  assert(sky.window == null);
+  sky.view.setBeginFrameCallback(_beginFrame);
+}
+
+void addPersistentFrameCallback(Callback callback) {
+  assert(sky.window == null);
+  _persistentCallbacks.add(callback);
+}
+
+int requestAnimationFrame(Callback callback) {
+  if (sky.window != null)
+    return sky.window.requestAnimationFrame(callback);
+  int id = _nextCallbackId++;
+  _transientCallbacks[id] = callback;
+  ensureVisualUpdate();
+  return id;
+}
+
+void cancelAnimationFrame(int id) {
+  if (sky.window != null)
+    return sky.window.cancelAnimationFrame(id);
+  _transientCallbacks.remove(id);
+}
+
+void ensureVisualUpdate() {
+  assert(sky.window == null);
+  if (_haveScheduledVisualUpdate)
+    return;
+  sky.view.scheduleFrame();
+  _haveScheduledVisualUpdate = true;
+}