sheriff: mark one SameSite test flaky on CrOS

Bug: 1156218
Change-Id: I7a1730f4e607418df9a6300eb143e02d30007507
Tbr: arthursonzogni@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2575832Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834313}

content/browser/renderer_host/render_frame_host_manager_browsertest.cc

@@ -7732,6 +7732,15 @@ IN_PROC_BROWSER_TEST_P(ProactivelySwapBrowsingInstancesSameSiteTest,
   }
 }
 
+#if defined(OS_CHROMEOS)
+// Quite flaky: https://crbug.com/1156218
+#define MAYBE_StorageModificationAfterPagehideHistogram \
+  DISABLED_StorageModificationAfterPagehideHistogram
+#else
+#define MAYBE_StorageModificationAfterPagehideHistogram \
+  StorageModificationAfterPagehideHistogram
+#endif
+
 IN_PROC_BROWSER_TEST_P(ProactivelySwapBrowsingInstancesSameSiteTest,
                        StorageModificationAfterPagehideHistogram) {
   ASSERT_TRUE(embedded_test_server()->Start());