Disable Autofill PrefillFormAndFill on Mac.

Test PrefillFormAndFill fails often on Mac, disabling now so we can
enable the other Mac tests.

Bug: 1141208
Change-Id: Ia4f9a09ced6484f4941f5683b4ae499c009d7452
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2490849
Commit-Queue: Dominic Battré <battre@chromium.org>
Reviewed-by: Dominic Battré <battre@chromium.org>
Auto-Submit: Ian Struiksma <ianstruiksma@google.com>
Cr-Commit-Position: refs/heads/master@{#819730}

chrome/browser/autofill/autofill_interactive_uitest.cc

@@ -912,7 +912,13 @@ IN_PROC_BROWSER_TEST_F(AutofillInteractiveTest, ModifySelectFieldAndFill) {
 }
 
 // Test that autofill works when the website prefills the form.
-IN_PROC_BROWSER_TEST_F(AutofillInteractiveTest, PrefillFormAndFill) {
+// TODO(crbug.com/1141208): Disabled due to flakiness on MAC
+#if defined(OS_MAC)
+#define MAYBE_PrefillFormAndFill DISABLED_PrefillFormAndFill
+#else
+#define MAYBE_PrefillFormAndFill PrefillFormAndFill
+#endif
+IN_PROC_BROWSER_TEST_F(AutofillInteractiveTest, MAYBE_PrefillFormAndFill) {
   const char kPrefillScript[] =
       "<script>"
       "document.getElementById('firstname').value = 'Seb';"