Convert IntersectionObserver tests to use testRunner.runIdleTasks.

third_party/WebKit/LayoutTests/resources/intersection-observer-helper-functions.js

Index: third_party/WebKit/LayoutTests/resources/intersection-observer-helper-functions.js
diff --git a/third_party/WebKit/LayoutTests/resources/intersection-observer-helper-functions.js b/third_party/WebKit/LayoutTests/resources/intersection-observer-helper-functions.js
new file mode 100644
index 0000000000000000000000000000000000000000..050274da18dcd5bff5bbd65d8f981fd1fb35c557
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/resources/intersection-observer-helper-functions.js
@@ -0,0 +1,109 @@
+// Some of the js-test.js boilerplate will add stuff to the top of the document early
+// enough to screw with frame offsets that are measured by the test.  Delay all that
+// jazz until the actual test code is finished.
+if (self.isJsTest) {
+  setPrintTestResultsLazily();
+  self.jsTestIsAsync = true;
+}
+
+// waitForNotification is a requestIdleCallback wrapped in a setTimeout wrapped in a
+// requestAnimationFrame.  What in the wide, wide world of sports is going on here?
+//
+// Here's the order of events:
+//
+// - firstTestFunction
+//   - Change layout to generate new IntersectionObserver notifications.
+//   - waitForNotification(secondTestFunction)
+//     - requestAnimationFrame
+// - BeginFrame
+//   - requestAnimationFrame handler runs.
+//     - setTimeout
+//   - FrameView::updateAllLifecyclePhases
+//     - IntersectionObserver generates notification based on the new layout.
+//       - Post idle task to deliver notification.
+//   - setTimeout handler runs.
+//     - testRunner.runIdleTasks or requestIdleCallback.
+//   - Idle tasks run -- more or less immediately if (self.testRunner),
+//     possibly delayed if (!self.testRunner).
+//     - IntersectionObserver notifications are delivered.
+//     - secondTestFunction
+//       - Verify notifications generated by firstTestFunction.
+//       - Change layout to generate new IntersectionObserver notifications.
+//       - waitForNotification(thirdTestFunction)
+//
+// Note that this should work equally well in these operation conditions:
+//
+//   - layout test using single-threaded compositing (the default)
+//   - layout test using multi-threaded compositing (virtual/threaded/)
+//   - Not in a layout test and using multi-threaded compositing (the only configuration we ship)
+function waitForNotification(f) {
+  requestAnimationFrame(() => {
+    setTimeout(() => {
+      if (self.testRunner)
+        testRunner.runIdleTasks(f);
+      else
+        requestIdleCallback(f);
+    });
+  });
+}
+
+function rectToString(rect) {
+  return "[" + rect.left + ", " + rect.right + ", " + rect.top + ", " + rect.bottom + "]";
+}
+
+function entryToString(entry) {
+  var ratio = ((entry.intersectionRect.width * entry.intersectionRect.height) /
+               (entry.boundingClientRect.width * entry.boundingClientRect.height));
+  return (
+      "boundingClientRect=" + rectToString(entry.boundingClientRect) + "\n" +
+      "intersectionRect=" + rectToString(entry.intersectionRect) + "\n" +
+      "visibleRatio=" + ratio + "\n" +
+      "rootBounds=" + rectToString(entry.rootBounds) + "\n" +
+      "target=" + entry.target + "\n" +
+      "time=" + entry.time);
+}
+
+function rectArea(rect) {
+  return (rect.left - rect.right) * (rect.bottom - rect.top);
+}
+
+function intersectionRatio(entry) {
+  var targetArea = rectArea(entry.boundingClientRect);
+  if (!targetArea)
+    return 0;
+  return rectArea(entry.intersectionRect) / targetArea;
+}
+
+function clientRectToJson(rect) {
+  if (!rect)
+    return null;
+  return {
+    top: rect.top,
+    right: rect.right,
+    bottom: rect.bottom,
+    left: rect.left,
+    width: rect.width,
+    height: rect.height
+  };
+}
+
+function coordinatesToClientRectJson(top, right, bottom, left) {
+  return {
+    top: top,
+    right: right,
+    bottom: bottom,
+    left: left,
+    width: right - left,
+    height: bottom - top
+  };
+}
+
+function entryToJson(entry) {
+  return {
+    boundingClientRect: clientRectToJson(entry.boundingClientRect),
+    intersectionRect: clientRectToJson(entry.intersectionRect),
+    rootBounds: clientRectToJson(entry.rootBounds),
+    time: entry.time,
+    target: entry.target.id
+  };
+}