[Sheriff] Disable flaky SamplingMallocShimsTest.BasicFunctionality on Mac

TBR=vitalybuka

Bug: 1087372
Change-Id: Ie4fce45671e166417f679b91ca9229968196983c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2220005Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#772658}

components/gwp_asan/client/sampling_malloc_shims_unittest.cc

@@ -167,7 +167,13 @@ MULTIPROCESS_TEST_MAIN_WITH_SETUP(
   return kFailure;
 }
 
-TEST_F(SamplingMallocShimsTest, BasicFunctionality) {
+// Flaky on Mac: https://crbug.com/1087372
+#if defined(OS_MACOSX)
+#define MAYBE_BasicFunctionality DISABLED_BasicFunctionality
+#else
+#define MAYBE_BasicFunctionality BasicFunctionality
+#endif
+TEST_F(SamplingMallocShimsTest, MAYBE_BasicFunctionality) {
   runTest("BasicFunctionality");
 }