[Sheriff] Disable flaky SitePerProcessBrowserTestWithSadFrameTabReload on Mac

Bug: 1049885
Change-Id: Icfc0c764791daaa9a0f60eece7818c1e5af5316d
Tbr: alexmos@chromium.org
NoTry: True
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2376381Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801611}

content/browser/site_per_process_browsertest.cc

@@ -13730,9 +13730,9 @@ class SitePerProcessBrowserTestWithSadFrameTabReload
 // reload. This avoids showing crashed subframes if a hidden tab is eventually
 // shown. See https://crbug.com/841572.
 // crbug.com/1010119, fails on Win. crbug.com/1015971, fails on Linux.
-// crbug.com/1049885, fails on Android.
+// crbug.com/1049885, fails on Android and Mac.
 #if defined(OS_WIN) || defined(OS_LINUX) || defined(OS_CHROMEOS) || \
-    defined(OS_ANDROID)
+    defined(OS_ANDROID) || defined(OS_MACOSX)
 #define MAYBE_ReloadHiddenTabWithCrashedSubframe \
   DISABLED_ReloadHiddenTabWithCrashedSubframe
 #else