Attempt to fix flaky timeout in resource_timing_buffer_full_eventually

This CL attempts to fix the flaky timeouts in the test
virtual/omt-worker-fetch/external/wpt/resource-timing/resource_timing_buffer_full_eventually.html
by doing the following:

1. Set it to be 'long'. This is a slow test due to the large amount of
fetches.
2. Set the number of elements added at a time to 8, which is faster than
100 in my experimentation.
3. Do not wait for onload to begin appending scripts.

Bug: 1041707
Change-Id: Iddf37a72135e1f82c23c3e71c8da40eca13b8f78
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2011294Reviewed-by: Kunihiko Sakamoto <ksakamoto@chromium.org>
Commit-Queue: Nicolás Peña Moreno <npm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#733502}

third_party/blink/web_tests/TestExpectations

@@ -1683,7 +1683,6 @@ crbug.com/891427 animations/responsive/viewport-unit-transform-responsive.html [
 crbug.com/891427 animations/responsive/viewport-unit-translate-responsive.html [ Pass Failure Timeout Crash ]
 crbug.com/891427 virtual/android/rootscroller/rootscroller-during-fullscreen.html [ Pass Failure Timeout Crash ]
 # Next 2 here: https://ci.chromium.org/buildbot/tryserver.blink/win7-blink-rel/1183
-crbug.com/891427 external/wpt/resource-timing/resource_timing_buffer_full_eventually.html [ Pass Failure Timeout Crash ]
 crbug.com/891427 fast/canvas/canvas-drawImage-live-video.html [ Pass Failure Timeout Crash ]
 crbug.com/816914 virtual/gpu/fast/canvas/canvas-drawImage-live-video.html [ Pass Failure Timeout Crash ]
 # Next 1 here: https://ci.chromium.org/buildbot/tryserver.blink/win7-blink-rel/1180
@@ -2964,8 +2963,6 @@ crbug.com/626703 [ Win ] external/wpt/css/css-text/word-break/word-break-keep-al
 crbug.com/626703 [ Mac10.11 ] external/wpt/shape-detection/idlharness.https.any.sharedworker.html [ Failure Timeout ]
 crbug.com/626703 [ Win7 ] external/wpt/pointerevents/pointerevent_touch-action-pan-y-css_touch.html [ Timeout ]
 crbug.com/626703 [ Win10 ] external/wpt/payment-request/payment-request-hasenrolledinstrument-method.tentative.https.html [ Failure Timeout ]
-crbug.com/626703 [ Mac10.10 ] virtual/omt-worker-fetch/external/wpt/resource-timing/resource_timing_buffer_full_eventually.html [ Timeout Pass Failure ]
-crbug.com/626703 [ Retina ] virtual/omt-worker-fetch/external/wpt/resource-timing/resource_timing_buffer_full_eventually.html [ Timeout Pass Failure ]
 crbug.com/626703 [ Win10 ] virtual/cascade/external/wpt/css/css-paint-api/color-custom-property-animation.https.html [ Failure ]
 crbug.com/626703 [ Mac10.11 ] virtual/omt-service-worker-startup/external/wpt/shape-detection/shapedetection-cross-origin.sub.https.html [ Timeout ]
 crbug.com/626703 [ Mac10.11 ] virtual/omt-service-worker-startup/external/wpt/shape-detection/detection-security-test.https.html [ Timeout ]
@@ -3296,7 +3293,6 @@ crbug.com/626703 external/wpt/css/css-will-change/will-change-abspos-cb-dynamic-
 crbug.com/626703 external/wpt/css/css-will-change/will-change-abspos-cb-001.html [ Failure ]
 crbug.com/626703 external/wpt/css/css-conditional/at-supports-040.html [ Failure ]
 ### See crbug.com/891427 comment near the top of this file:
-###crbug.com/626703 [ Win7 ] external/wpt/resource-timing/resource_timing_buffer_full_eventually.html [ Timeout ]
 crbug.com/626703 external/wpt/html/rendering/non-replaced-elements/the-fieldset-and-legend-elements/legend-block-margins-2.html [ Failure ]
 crbug.com/626703 external/wpt/webvtt/rendering/cues-with-video/processing-model/align_center.html [ Failure ]
 crbug.com/626703 external/wpt/webvtt/rendering/cues-with-video/processing-model/align_center_position_50.html [ Failure ]
@@ -5865,8 +5861,6 @@ crbug.com/979422 [ Mac ] fast/borders/border-radius-mask-canvas.html [ Failure ]
 crbug.com/979422 [ Mac ] fast/borders/border-radius-mask-canvas-with-mask.html [ Failure ]
 crbug.com/979422 [ Mac ] fast/borders/border-radius-mask-canvas-border.html [ Failure ]
 crbug.com/989014 [ Linux Debug ] external/wpt/cookie-store/serviceworker_cookiechange_eventhandler_single_subscription.tentative.https.any.serviceworker.html [ Pass Timeout ]
-crbug.com/989665 [ Win ] virtual/omt-worker-fetch/external/wpt/resource-timing/resource_timing_buffer_full_eventually.html [ Pass Timeout ]
-crbug.com/989665 [ Linux ] virtual/omt-worker-fetch/external/wpt/resource-timing/resource_timing_buffer_full_eventually.html [ Pass Timeout ]
 
 # Sheriff 2019-08-01
 crbug.com/989860 [ Mac10.13 ] http/tests/devtools/indexeddb/live-update-indexeddb-list.js [ Pass Failure ]

third_party/blink/web_tests/external/wpt/resource-timing/resource_timing_buffer_full_eventually.html

@@ -4,6 +4,7 @@
 <meta charset="utf-8" />
 <link rel="help" href="http://www.w3.org/TR/resource-timing/#performanceresourcetiming"/>
 <title>This test validates that resource timing implementations have a finite number of entries in their buffer.</title>
+<meta name="timeout" content="long">
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 </head>
@@ -12,28 +13,24 @@
     const t = async_test("Finite resource timing entries buffer size");
     performance.onresourcetimingbufferfull = t.step_func_done(function() {
     });
-    window.onload = t.step_func(
-        function() {
-            // Scripts appended in JS to ensure setResourceTimingBufferSize is called before.
-            let counter = performance.getEntriesByType("resource").length;
-            function appendScripts() {
-                const documentFragment = document.createDocumentFragment();
-                // Add 100 elements at a time to avoid page reflow every time.
-                let numScriptsAccumulated = 0;
-                while (numScriptsAccumulated < 100) {
-                    const src = "resources/empty.js?" + counter;
-                    const script = document.createElement('script');
-                    script.type = 'text/javascript';
-                    script.src = src;
-                    documentFragment.appendChild(script);
-                    ++counter;
-                    ++numScriptsAccumulated;
-                }
-                document.body.appendChild(documentFragment);
-                t.step_timeout(appendScripts, 20);
-            }
-            appendScripts();
-        });
+    let counter = 0;
+    function appendScripts() {
+        const documentFragment = document.createDocumentFragment();
+        // Add 8 elements at a time to avoid page reflow every time.
+        let numScriptsAccumulated = 0;
+        while (numScriptsAccumulated < 8) {
+            const src = "resources/empty.js?" + counter;
+            const script = document.createElement('script');
+            script.type = 'text/javascript';
+            script.src = src;
+            documentFragment.appendChild(script);
+            ++counter;
+            ++numScriptsAccumulated;
+        }
+        document.body.appendChild(documentFragment);
+        t.step_timeout(appendScripts, 20);
+    }
+    appendScripts();
 </script>
 </body>
 </html>