Simulate user inputs in css-scroll-snap/snap-at-user-scroll-end.html

Use testdriver Action API to simulate wheel scroll actions in
css/css-scroll-snap/snap-at-user-scroll-end.html.

Bug: 1145677
Change-Id: I56d99d22a325419865fdc18dfa4cf0a3ae55df51

css/css-scroll-snap/snap-at-user-scroll-end-manual.html → css/css-scroll-snap/snap-at-user-scroll-end.html

@@ -3,8 +3,11 @@
 <title>Tests that window should snap at user scroll end.</title>
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
+<script src="/resources/testdriver.js"></script>
+<script src="/resources/testdriver-actions.js"></script>
+<script src="/resources/testdriver-vendor.js"></script>
 <style>
-body {
+html {
   margin: 0px;
   scroll-snap-type: both mandatory;
 }
@@ -55,6 +58,38 @@ <h4>Tests that the window can snap at user scroll end.</h4>
 var scrolled_y = false;
 var start_x = window.scrollX;
 var start_y = window.scrollY;
+var actions_promise;
+
+function smoothScrollByXY(xPosition, yPosition, xScrollOffset, yScrollOffset) {
+  return new test_driver.Actions()
+      .scroll(xPosition, yPosition, xScrollOffset, yScrollOffset)
+      .send();
+}
+
+function waitForAnimationEnd() {
+  const MAX_FRAME = 500;
+  var last_changed_frame = 0;
+  var last_window_x = window.scrollX;
+  var last_window_y = window.scrollY;
+  return new Promise((resolve, reject) => {
+    function tick(frames) {
+      // We requestAnimationFrame either for 500 frames or until 15 frames with
+      // no change have been observed.
+      if (frames >= MAX_FRAME || frames - last_changed_frame > 15) {
+        resolve();
+      } else {
+        if (window.scrollX != last_window_x ||
+            window.scrollY != last_window_y) {
+          last_changed_frame = frames;
+          last_window_x = window.scrollX;
+          last_window_y = window.scrollY;
+        }
+        requestAnimationFrame(tick.bind(this, frames + 1));
+      }
+    }
+    tick(0);
+  });
+}
 
 window.onscroll = function() {
   if (scrolled_x && scrolled_y) {
@@ -84,7 +119,17 @@ <h4>Tests that the window can snap at user scroll end.</h4>
   // To make the test result visible.
   var content = document.getElementById("content");
   body.removeChild(content);
-  snap_test.done();
+  actions_promise.then( () => {
+    snap_test.done();
+  });
 }
 
+// Inject scroll actions.
+actions_promise = new test_driver.Actions()
+    .scroll(20, 20, 100, 100)
+    .send().then(() => {
+  return waitForAnimationEnd();
+}).then(() => {
+  return test_driver.click(button);
+});
 </script>