Disable flaky AppBannerManagerBrowserTest.MissingManifest

Bug: 1146526
Change-Id: I336c6989e35b3b25cd9706a843b0d007152d647a
NoTry: True
Tbr: dominickn@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2523480
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824977}

chrome/browser/banners/app_banner_manager_browsertest.cc

@@ -383,7 +383,13 @@ IN_PROC_BROWSER_TEST_F(AppBannerManagerBrowserTest, NoManifest) {
       NO_MANIFEST);
 }
 
-IN_PROC_BROWSER_TEST_F(AppBannerManagerBrowserTest, MissingManifest) {
+// TODO(crbug.com/1146526): Test is flaky on Mac.
+#if defined(OS_MAC)
+#define MAYBE_MissingManifest DISABLED_MissingManifest
+#else
+#define MAYBE_MissingManifest MissingManifest
+#endif
+IN_PROC_BROWSER_TEST_F(AppBannerManagerBrowserTest, MAYBE_MissingManifest) {
   std::unique_ptr<AppBannerManagerTest> manager(
       CreateAppBannerManager(browser()));
   RunBannerTest(browser(), manager.get(),