TaskScheduler: Enable NoBackgroundTasksTest.* on Mac.

Bug: 833989
Change-Id: Id97ab3cf302067670b5a90e38d2077f1b7b3e89e
Reviewed-on: https://chromium-review.googlesource.com/1231299Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: François Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592844}

chrome/browser/no_background_tasks_browsertest.cc

@@ -59,11 +59,9 @@ class NoBackgroundTasksTest : public InProcessBrowserTest {
 // background tasks.
 //
 // TODO(fdoray) https://crbug.com/833989:
-// - Flaky timeout on Mac
 // - Flaky timeout on ChromeOS ASAN
 // - Consistent timeout on Win ASAN
-#if defined(OS_MACOSX) || \
-    (defined(ADDRESS_SANITIZER) && (defined(OS_CHROMEOS) || defined(OS_WIN)))
+#if defined(ADDRESS_SANITIZER) && (defined(OS_CHROMEOS) || defined(OS_WIN))
 #define MAYBE_FirstNonEmptyPaintWithoutBackgroundTasks \
   DISABLED_FirstNonEmptyPaintWithoutBackgroundTasks
 #else

testing/buildbot/filters/webui_polymer2_browser_tests.filter

@@ -285,6 +285,7 @@ MultiDeviceSetupBrowserTest.*
 MultiProfileDriveFileSystemExtensionApiTest.*
 MultiProfileFilesAppBrowserTest.*
 NetInternalsTest.*
+NoBackgroundTasksTest.*
 NTP4WebUITest.*
 PasswordsAndFormsBrowserTest.*
 PrintPreviewAdvancedDialogTest.*