Disable flaky test AppBannerManagerDesktopBrowserTest.WebAppBannerFiresAppInstalled

Bug: 988292
Change-Id: If4911cb53528913b6cccf5c4db9784e4e04c3d98
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1722362
Auto-Submit: Alan Cutter <alancutter@chromium.org>
Commit-Queue: Dominick Ng <dominickn@chromium.org>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#681712}

chrome/browser/banners/app_banner_manager_desktop_browsertest.cc

@@ -156,8 +156,9 @@ IN_PROC_BROWSER_TEST_F(AppBannerManagerDesktopBrowserTest,
   EXPECT_EQ(title, watcher.WaitAndGetTitle());
 }
 
+// TODO(crbug.com/988292): Flakes on most platforms.
 IN_PROC_BROWSER_TEST_F(AppBannerManagerDesktopBrowserTest,
-                       WebAppBannerFiresAppInstalled) {
+                       DISABLED_WebAppBannerFiresAppInstalled) {
   content::WebContents* web_contents =
       browser()->tab_strip_model()->GetActiveWebContents();
   auto* manager =