Disable BrowserCloseManagerBrowserTest.AddBeforeUnloadDuringClosing on Mac.

chrome/browser/lifetime/browser_close_manager_browsertest.cc

Index: chrome/browser/lifetime/browser_close_manager_browsertest.cc
diff --git a/chrome/browser/lifetime/browser_close_manager_browsertest.cc b/chrome/browser/lifetime/browser_close_manager_browsertest.cc
index 63bbc8654d0139a4b20b1e6c75ad46da77a869f2..65c5d43cc0e5047b11bc5021a42c9c18f7910402 100644
--- a/chrome/browser/lifetime/browser_close_manager_browsertest.cc
+++ b/chrome/browser/lifetime/browser_close_manager_browsertest.cc
@@ -741,8 +741,16 @@ IN_PROC_BROWSER_TEST_P(BrowserCloseManagerBrowserTest,
   EXPECT_TRUE(BrowserList::GetInstance()->empty());
 }
 
+// TODO(crbug/713201):
+// BrowserCloseManagerBrowserTest.AddBeforeUnloadDuringClosing flaky on Mac.
+#if defined(OS_MACOSX)
+#define MAYBE_AddBeforeUnloadDuringClosing DISABLED_AddBeforeUnloadDuringClosing
+#else
+#define MAYBE_AddBeforeUnloadDuringClosing AddBeforeUnloadDuringClosing
+#endif
+
 IN_PROC_BROWSER_TEST_P(BrowserCloseManagerBrowserTest,
-                       AddBeforeUnloadDuringClosing) {
+                       MAYBE_AddBeforeUnloadDuringClosing) {
   // TODO(crbug.com/250305): Currently FastUnloadController is broken.
   // And it is difficult to fix this issue without fixing that one.
   if (GetParam())