Hide low space warning banners during tests

These cause flakes during *tabindex* integration tests.

Bug: 1139247
Change-Id: I56024c545e254c35ab0d20ff6009358b700c0e1d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2520482Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: Austin Tankiang <austinct@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825235}

chrome/browser/chromeos/file_manager/file_manager_browsertest.cc

@@ -781,14 +781,8 @@ WRAPPED_INSTANTIATE_TEST_SUITE_P(
     ::testing::Values(TestCase("sortColumns"),
                       TestCase("sortColumns").InGuestMode()));
 
-// TODO(crbug.com/1139247): Failing on ChromeOS.
-#if defined(OS_CHROMEOS)
-#define MAYBE_TabIndex DISABLED_TabIndex
-#else
-#define MAYBE_TabIndex TabIndex
-#endif
 WRAPPED_INSTANTIATE_TEST_SUITE_P(
-    MAYBE_TabIndex, /* tab_index.js: */
+    TabIndex, /* tab_index.js: */
     FilesAppBrowserTest,
     ::testing::Values(
         TestCase("tabindexSearchBoxFocus").FilesNg(),

ui/file_manager/file_manager/foreground/js/ui/banners.js

@@ -646,6 +646,12 @@ class Banners extends cr.EventTarget {
    * @private
    */
   maybeShowLowSpaceWarning_(volume) {
+    // Never show low space warning banners in a test as it will cause flakes.
+    // TODO(crbug.com/1146265): Somehow figure out a way to test these banners.
+    if (window.IN_TEST) {
+      return;
+    }
+
     // TODO(kaznacheev): Unify the two low space warning.
     switch (volume.volumeType) {
       case VolumeManagerCommon.VolumeType.DOWNLOADS: