Disable flaky test scrollbars/scrollbar-mousedown-move-mouseup.html

We found that the test
scrolling/scrollbars/scrollbar-mousedown-move-mouseup.html is flaky when
the scroll unification flag is enabled. Below is the failing reason,
scroll_manager.cc(548) Check failed:
!RuntimeEnabledFeatures::ScrollUnificationEnabled().
blink::ScrollManager::HandleGestureScrollUpdate()
blink::ScrollManager::HandleGestureScrollEvent()
blink::EventHandler::HandleGestureScrollEvent()
blink::WebViewImpl::HandleGestureEvent()
blink::PageWidgetDelegate::HandleInputEvent()
blink::WebViewImpl::HandleInputEvent()

We will disable it for now until we fix this problem for scrollbar.


Bug: 1130020
Change-Id: Icd4b0aede785d35598cd3d7b901b032c2d23c5e8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2533476
Commit-Queue: Lan Wei <lanwei@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826950}

third_party/blink/web_tests/TestExpectations

@@ -6280,3 +6280,7 @@ crbug.com/1146560 [ Win ] fast/canvas/color-space/canvas-createImageBitmap-e_srg
 
 # Sheriff 2020-11-12
 crbug.com/1148259 [ Mac ] external/wpt/html/browsers/browsing-the-web/navigating-across-documents/javascript-url-return-value-handling-dynamic.html [ Failure ]
+
+# Disable flaky tests when scroll unification is enabled
+crbug.com/1130020 virtual/scroll-unification/fast/scrolling/scrollbars/scrollbar-mousedown-move-mouseup.html [ Pass Failure Timeout ]
+crbug.com/1130020 virtual/threaded-prefer-compositing/fast/scrolling/scrollbars/scrollbar-mousedown-move-mouseup.html [ Pass Failure Timeout ]