[ios] Fixes testSignInPromoWithColdStateUsingPrimaryButton.

This test attempts to tap a "Cancel" button in a mock signin promo view. When
the UIRefresh flag is enabled, there are multiple "Cancel" buttons present in
the view hierarchy. This CL fixes the issue by adding
grey_sufficientlyVisible().

BUG=818742

Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: Id59c25b24b46e83552bafbfa22e6bc96676008c5
Reviewed-on: https://chromium-review.googlesource.com/1007254
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Commit-Queue: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549909}
1 file changed