Do not check tray bounds in LoginTests with Mash

This expectation fails due to the button which is showing with
Mash. This is basically for developers, so it's okay to skip
the checks.

BUG=892730
TEST=interactive_ui_tests

Change-Id: Ibebe65891bdbb1d9539e89f42114c39435ff2737
Reviewed-on: https://chromium-review.googlesource.com/c/1265895Reviewed-by: James Cook <jamescook@chromium.org>
Commit-Queue: Jun Mukai <mukai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597340}

chrome/browser/chromeos/login/login_browsertest.cc

@@ -44,6 +44,7 @@
 #include "extensions/browser/extension_system.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "ui/base/ui_base_features.h"
 #include "ui/gfx/geometry/test/rect_test_util.h"
 
 using ::gfx::test::RectContains;
@@ -199,7 +200,11 @@ void TestSystemTrayIsVisible(bool otr) {
   EXPECT_TRUE(tray->visible());
 
   // This check flakes for LoginGuestTest: https://crbug.com/693106.
-  if (!otr)
+  // This check is suppressed for Mash since the warning button of Mash changes
+  // the tray bounds which triggers the failure. See: https://crbug.com/892730
+  // TODO(jamescook): remove this when Mash is on by default or the button is
+  // removed.
+  if (!otr && !features::IsUsingWindowService())
     EXPECT_TRUE(RectContains(primary_win->bounds(), tray->GetBoundsInScreen()));
 }