IntersectionObserver: use an idle callback to send notifications.

third_party/WebKit/LayoutTests/intersection-observer/iframe-no-root.html

Index: third_party/WebKit/LayoutTests/intersection-observer/iframe-no-root.html
diff --git a/third_party/WebKit/LayoutTests/intersection-observer/iframe-no-root.html b/third_party/WebKit/LayoutTests/intersection-observer/iframe-no-root.html
index 912e286fa7deb01f3be509eb7ca27988e4755145..a711cc25c19aa658f0e464279e03539d35910cd2 100644
--- a/third_party/WebKit/LayoutTests/intersection-observer/iframe-no-root.html
+++ b/third_party/WebKit/LayoutTests/intersection-observer/iframe-no-root.html
@@ -8,81 +8,77 @@
 <script>
 description("Simple intersection observer test with no explicit root and target in an iframe.");
 var entries = [];
+var observer = new IntersectionObserver(changes => { entries = entries.concat(changes) }, {});
 var targetIframe = document.getElementById("target-iframe");
+var target;
+var iframeScroller;
 
 targetIframe.onload = function() {
-  var target = targetIframe.contentDocument.getElementById("target");
-  var iframeScroller = targetIframe.contentDocument.scrollingElement;
-
-  observer_callback = function(changes) {
-    for (var i in changes)
-      entries.push(changes[i]);
-  };
-  var observer = new IntersectionObserver(observer_callback, {});
+  target = targetIframe.contentDocument.getElementById("target");
+  iframeScroller = targetIframe.contentDocument.scrollingElement;
   observer.observe(target);
+  entries = entries.concat(observer.takeRecords());
+  shouldBeEqualToNumber("entries.length", 0);
+  // See README for explanation of double RAF.
+  requestAnimationFrame(() => { requestAnimationFrame(step0) });
+}
 
-  function step0() {
-    setTimeout(function() {
-      shouldBeEqualToNumber("entries.length", 0);
-      document.scrollingElement.scrollTop = 200;
-      requestAnimationFrame(step1);
-    });
-  }
+function step0() {
+  entries = entries.concat(observer.takeRecords());
+  shouldBeEqualToNumber("entries.length", 0);
+  document.scrollingElement.scrollTop = 200;
+  requestAnimationFrame(step1);
+}
 
-  function step1() {
-    setTimeout(function() {
-      shouldBeEqualToNumber("entries.length", 0);
-      iframeScroller.scrollTop = 250;
-      requestAnimationFrame(step2);
-    });
-  }
+function step1() {
+  entries = entries.concat(observer.takeRecords());
+  shouldBeEqualToNumber("entries.length", 0);
+  iframeScroller.scrollTop = 250;
+  requestAnimationFrame(step2);
+}
 
-  function step2() {
-    setTimeout(function() {
-      shouldBeEqualToNumber("entries.length", 1);
-      if (entries.length > 0) {
-        shouldBeEqualToNumber("entries[0].boundingClientRect.left", 8);
-        shouldBeEqualToNumber("entries[0].boundingClientRect.right", 108);
-        shouldBeEqualToNumber("entries[0].boundingClientRect.top", -42);
-        shouldBeEqualToNumber("entries[0].boundingClientRect.bottom", 58);
-        shouldBeEqualToNumber("entries[0].intersectionRect.left", 8);
-        shouldBeEqualToNumber("entries[0].intersectionRect.right", 108);
-        shouldBeEqualToNumber("entries[0].intersectionRect.top", 0);
-        shouldBeEqualToNumber("entries[0].intersectionRect.bottom", 58);
-        shouldBeEqualToNumber("entries[0].rootBounds.left", 0);
-        shouldBeEqualToNumber("entries[0].rootBounds.right", 785);
-        shouldBeEqualToNumber("entries[0].rootBounds.top", 0);
-        shouldBeEqualToNumber("entries[0].rootBounds.bottom", 600);
-        shouldEvaluateToSameObject("entries[0].target", target);
-      }
-      document.scrollingElement.scrollTop = 100;
-      requestAnimationFrame(step3);
-    });
+function step2() {
+  entries = entries.concat(observer.takeRecords());
+  shouldBeEqualToNumber("entries.length", 1);
+  if (entries.length > 0) {
+    shouldBeEqualToNumber("entries[0].boundingClientRect.left", 8);
+    shouldBeEqualToNumber("entries[0].boundingClientRect.right", 108);
+    shouldBeEqualToNumber("entries[0].boundingClientRect.top", -42);
+    shouldBeEqualToNumber("entries[0].boundingClientRect.bottom", 58);
+    shouldBeEqualToNumber("entries[0].intersectionRect.left", 8);
+    shouldBeEqualToNumber("entries[0].intersectionRect.right", 108);
+    shouldBeEqualToNumber("entries[0].intersectionRect.top", 0);
+    shouldBeEqualToNumber("entries[0].intersectionRect.bottom", 58);
+    shouldBeEqualToNumber("entries[0].rootBounds.left", 0);
+    shouldBeEqualToNumber("entries[0].rootBounds.right", 785);
+    shouldBeEqualToNumber("entries[0].rootBounds.top", 0);
+    shouldBeEqualToNumber("entries[0].rootBounds.bottom", 600);
+    shouldEvaluateToSameObject("entries[0].target", target);
   }
+  document.scrollingElement.scrollTop = 100;
+  requestAnimationFrame(step3);
+}
 
-  function step3() {
-    setTimeout(function() {
-      shouldBeEqualToNumber("entries.length", 2);
-      if (entries.length > 1) {
-        shouldBeEqualToNumber("entries[1].boundingClientRect.left", 8);
-        shouldBeEqualToNumber("entries[1].boundingClientRect.right", 108);
-        shouldBeEqualToNumber("entries[1].boundingClientRect.top", -42);
-        shouldBeEqualToNumber("entries[1].boundingClientRect.bottom", 58);
-        shouldBeEqualToNumber("entries[1].intersectionRect.left", 0);
-        shouldBeEqualToNumber("entries[1].intersectionRect.right", 0);
-        shouldBeEqualToNumber("entries[1].intersectionRect.top", 0);
-        shouldBeEqualToNumber("entries[1].intersectionRect.bottom", 0);
-        shouldBeEqualToNumber("entries[1].rootBounds.left", 0);
-        shouldBeEqualToNumber("entries[1].rootBounds.right", 785);
-        shouldBeEqualToNumber("entries[1].rootBounds.top", 0);
-        shouldBeEqualToNumber("entries[1].rootBounds.bottom", 600);
-        shouldEvaluateToSameObject("entries[1].target", target);
-      }
-      finishJSTest();
-      document.scrollingElement.scrollTop = 0;
-    });
+function step3() {
+  entries = entries.concat(observer.takeRecords());
+  shouldBeEqualToNumber("entries.length", 2);
+  if (entries.length > 1) {
+    shouldBeEqualToNumber("entries[1].boundingClientRect.left", 8);
+    shouldBeEqualToNumber("entries[1].boundingClientRect.right", 108);
+    shouldBeEqualToNumber("entries[1].boundingClientRect.top", -42);
+    shouldBeEqualToNumber("entries[1].boundingClientRect.bottom", 58);
+    shouldBeEqualToNumber("entries[1].intersectionRect.left", 0);
+    shouldBeEqualToNumber("entries[1].intersectionRect.right", 0);
+    shouldBeEqualToNumber("entries[1].intersectionRect.top", 0);
+    shouldBeEqualToNumber("entries[1].intersectionRect.bottom", 0);
+    shouldBeEqualToNumber("entries[1].rootBounds.left", 0);
+    shouldBeEqualToNumber("entries[1].rootBounds.right", 785);
+    shouldBeEqualToNumber("entries[1].rootBounds.top", 0);
+    shouldBeEqualToNumber("entries[1].rootBounds.bottom", 600);
+    shouldEvaluateToSameObject("entries[1].target", target);
   }
-
-  step0();
+  // See README for explanation of this requestIdleCallback.
+  requestIdleCallback(finishJSTest, {timeout: 100});
+  document.scrollingElement.scrollTop = 0;
 }
 </script>