Sheriff: Disable HostedAppPWAOnlyTest.ShouldNotShowToolbarForSystemWebAppInChrome

On Linux/Chrome OS debug bots

TBR=harrisjay@chromium.org
TBR=benwells@chromium.org

Bug: 966834
Change-Id: I3244d6298c704d9afa755c090829f82c4f10cf4d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1628749
Commit-Queue: Roman Sorokin [CET] <rsorokin@chromium.org>
Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#663066}

chrome/browser/ui/extensions/hosted_app_browsertest.cc

@@ -1614,10 +1614,18 @@ IN_PROC_BROWSER_TEST_P(HostedAppPWAOnlyTest, ShouldShowToolbarForSystemApp) {
   NavigateAndCheckForToolbar(app_browser_, app_url, false);
 }
 
+#if (defined(OS_LINUX) || defined(OS_CHROMEOS)) && !defined(NDEBUG)
+// https://crbug.com/966834. Flaky on Linux/Chrome OS debug bots.
+#define MAYBE_ShouldNotShowToolbarForSystemWebAppInChrome \
+  DISABLED_ShouldNotShowToolbarForSystemWebAppInChrome
+#else
+#define MAYBE_ShouldNotShowToolbarForSystemWebAppInChrome \
+  ShouldNotShowToolbarForSystemWebAppInChrome
+#endif
 // Check the toolbar is not shown for system web apps for pages on the chrome://
 // scheme.
 IN_PROC_BROWSER_TEST_P(HostedAppPWAOnlyTest,
-                       ShouldNotShowToolbarForSystemWebAppInChrome) {
+                       MAYBE_ShouldNotShowToolbarForSystemWebAppInChrome) {
   const GURL app_url(chrome::kChromeUISettingsURL);
 
   SetupSystemAppWithURL(app_url);