[ElementTiming] Do not expose elements in Shadow Trees

We initially exposed these elements but this seems to break design invariants. It is still unclear what we can do with elements in shadow trees, but for now it is safest to not expose them at all. Relevant threads: WICG/element-timing#3 WICG/webcomponents#816 Bug: 879270 Change-Id: Id4c0d65e0f0e086c6c6dfa29cc019a4c1ef6ab1f Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1622470 Reviewed-by: Chris Harrelson <chrishtr@chromium.org> Commit-Queue: Nicolás Peña Moreno <npm@chromium.org> Cr-Commit-Position: refs/heads/master@{#662391}
web-platform-tests · May 22, 2019 · 6272cd0 · 6272cd0
1 parent 0f00529
commit 6272cd0
Showing 1 changed file with 7 additions and 9 deletions.
diff --git a/element-timing/observe-shadow-image.html b/element-timing/observe-shadow-image.html
@@ -1,6 +1,6 @@
 <!DOCTYPE HTML>
 <meta charset=utf-8>
-<title>Element Timing: observe image in shadow tree</title>
+<title>Element Timing: do not observe image in shadow tree</title>
 <style>
 body {
   margin: 0;
@@ -19,13 +19,7 @@
     }
     const observer = new PerformanceObserver(
       t.step_func_done(function(entryList) {
-        assert_equals(entryList.getEntries().length, 1);
-        const entry = entryList.getEntries()[0];
-        const pathname = window.location.origin + '/element-timing/resources/square100.png';
-        checkElement(entry, pathname, 'my_image', 'my_id', beforeRender, img);
-        // Assume viewport has size at least 100, so the element is fully visible.
-        checkRect(entry, [0, 100, 0, 100]);
-        checkNaturalSize(entry, 100, 100);
+        assert_unreached('Should not observe elements in shadow trees!');
       })
     );
     observer.observe({entryTypes: ['element']});
@@ -40,6 +34,10 @@
       const shadowRoot = document.getElementById('target').attachShadow({mode: 'closed'});
       shadowRoot.appendChild(img);
       beforeRender = performance.now();
+      t.step_timeout(() => {
+        // Assume entry was not dispatched, so test passes.
+        t.done();
+      }, 500);
     };
-  }, 'Image in shadow tree with elementtiming attribute is observable.');
+  }, 'Image in shadow tree with elementtiming attribute is not observable.');
 </script>