Disable renameNewFolderDownloads* on Mash

Bug reported these tests flaking on Mash, but these tests got disabled
on all bots. Disable them on Mash, not everywhere.

Tbr: xidachen@chromium.org
Bug: 874954, 410163
Change-Id: I80eb7b2cb185063d2e3e752fa0ae47d39fc97035
Reviewed-on: https://chromium-review.googlesource.com/1179427
Commit-Queue: Noel Gordon <noel@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583973}

chrome/browser/chromeos/file_manager/file_manager_browsertest.cc

@@ -264,8 +264,7 @@ WRAPPED_INSTANTIATE_TEST_CASE_P(
                       TestCase("renameFileDownloads"),
                       TestCase("renameFileDrive"),
                       TestCase("renameFileDrive").EnableDriveFs(),
-                      // https://crbug.com/874954, failed on MSan bots.
-                      // TestCase("renameNewFolderDownloads").InGuestMode(),
+                      TestCase("renameNewFolderDownloads").InGuestMode(),
                       TestCase("renameNewFolderDownloads"),
                       TestCase("renameNewFolderDrive"),
                       TestCase("renameNewFolderDrive").EnableDriveFs()));

testing/buildbot/filters/mash.browser_tests.filter

@@ -309,4 +309,9 @@
 # https://crbug.com/671891
 -SiteDetailsBrowserTest.IsolateExtensions
 
+# Started flaking on MSAN Mash browser_tests bots for the Downloads case (Drive
+# tests cases are fine), https://crbug.com/874954
+-KeyboardOperations/FilesAppBrowserTest.Test/renameNewFolderDownloads
+-KeyboardOperations/FilesAppBrowserTest.Test/renameNewFolderDownloads_GuestMode
+
 # See comment at top of file regarding adding test exclusions.