sheriff: disable CorbAndCorsExtensionBrowserTest test on Mac

It is flaky under ASAN.

Bug: 1082355
Change-Id: I8173311710c4b78268e35501bd9137497cbbcd98
Tbr: lazyboy@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2264594Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#781908}

chrome/browser/extensions/corb_and_cors_extension_browsertest.cc

@@ -1704,8 +1704,9 @@ IN_PROC_BROWSER_TEST_P(CorbAndCorsExtensionBrowserTest,
   }
 }
 
-#if defined(OS_LINUX) || defined(OS_WIN)
+#if defined(OS_LINUX) || defined(OS_WIN) || defined(OS_MACOSX)
 // Flaky on Linux, especially under sanitizers: https://crbug.com/1073052
+// Flaky UAF on Mac under ASAN: https://crbug.com/1082355
 #define MAYBE_FromBackgroundServiceWorker_NoSniffXml \
   DISABLED_FromBackgroundServiceWorker_NoSniffXml
 #else