Skip WindowCapturerTest.Capture on macOS.

Bug: webrtc:12801
Change-Id: I543313f3c304b694cc50bff5a6344f1c6d944c8d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/219635
Reviewed-by: Artem Titov <titovartem@webrtc.org>
Reviewed-by: Joe Downing <joedow@chromium.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34103}
diff --git a/modules/desktop_capture/window_capturer_unittest.cc b/modules/desktop_capture/window_capturer_unittest.cc
index 8a611e7..3989c28 100644
--- a/modules/desktop_capture/window_capturer_unittest.cc
+++ b/modules/desktop_capture/window_capturer_unittest.cc
@@ -54,8 +54,9 @@
   }
 }
 
-// Flaky on Linux. See: crbug.com/webrtc/7830
-#if defined(WEBRTC_LINUX)
+// Flaky on Linux. See: crbug.com/webrtc/7830.
+// Failing on macOS 11: See bugs.webrtc.org/12801
+#if defined(WEBRTC_LINUX) || defined(WEBRTC_MAC)
 #define MAYBE_Capture DISABLED_Capture
 #else
 #define MAYBE_Capture Capture