[Sheriff] Disable *.MixedContentSettings_AllowRunningInsecureContent

SSLUIWorkerFetchTest.MixedContentSettings_AllowRunningInsecureContent/*
is flaky on multiple platforms:
https://analysis.chromium.org/p/chromium/flake-portal/flakes/occurrences?key=ag9zfmZpbmRpdC1mb3ItbWVyZwsSBUZsYWtlIlxjaHJvbWl1bUBicm93c2VyX3Rlc3RzQFNTTFVJV29ya2VyRmV0Y2hUZXN0Lk1peGVkQ29udGVudFNldHRpbmdzX0FsbG93UnVubmluZ0luc2VjdXJlQ29udGVudAw

TBR=agl@chromium.org

Bug: 1145674
Change-Id: Ia5fad8376367f7a541290f7fed7fa173514f6ab6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2519588Reviewed-by: Adam Langley <agl@chromium.org>
Reviewed-by: Sahel Sharify <sahel@chromium.org>
Commit-Queue: Sahel Sharify <sahel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824155}

chrome/browser/ssl/ssl_browsertest.cc

@@ -3720,8 +3720,10 @@ IN_PROC_BROWSER_TEST_P(SSLUIWorkerFetchTest,
 // This test checks the behavior of mixed content blocking for the requests
 // from a dedicated worker by changing the settings in WebPreferences
 // with allow_running_insecure_content = true.
-IN_PROC_BROWSER_TEST_P(SSLUIWorkerFetchTest,
-                       MixedContentSettings_AllowRunningInsecureContent) {
+// Flaky. See https://crbug.com/1145674.
+IN_PROC_BROWSER_TEST_P(
+        SSLUIWorkerFetchTest,
+        DISABLED_MixedContentSettings_AllowRunningInsecureContent) {
   ChromeContentBrowserClientForMixedContentTest browser_client;
   content::ContentBrowserClient* old_browser_client =
       content::SetBrowserClientForTesting(&browser_client);