[sheriff] Disable AdsPageLoadMetricsObserverBrowserTest.FirstContentfulPaintRecorded

TBR=fdoray@chromium.org

Bug: 1090976
Change-Id: I57f4916e5373d48c0128d95237e2e05f7fff3009
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2228657Reviewed-by: François Doray <fdoray@chromium.org>
Reviewed-by: Josh Karlin <jkarlin@chromium.org>
Commit-Queue: François Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#774896}

chrome/browser/page_load_metrics/observers/ad_metrics/ads_page_load_metrics_observer_browsertest.cc

@@ -562,8 +562,12 @@ IN_PROC_BROWSER_TEST_F(AdsPageLoadMetricsObserverBrowserTest, FrameDepth) {
 }
 
 // Test that an ad frame with visible resource gets a FCP.
+//
+// This test is flaky on multiple platforms https://crbug.com/1090976
+// TODO(https://crbug.com/1090976): Wait until the histogram is recorded instead
+// of until 4 resources are complete.
 IN_PROC_BROWSER_TEST_F(AdsPageLoadMetricsObserverBrowserTest,
-                       FirstContentfulPaintRecorded) {
+                       DISABLED_FirstContentfulPaintRecorded) {
   SetRulesetWithRules(
       {subresource_filter::testing::CreateSuffixRule("pixel.png")});
   base::HistogramTester histogram_tester;