[Nav Experiment] Add a wait after restore session.

This fixes WebViewRestorableStateTest when WKBasedNavigationManger is
enabled. A better approach would be to turn this test into a
programmatic test so both navigation managers implementations are
tested, but web::features symbols are not exposed in ios/web_view.

Bug: 862714
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I19916a973b566fac32c8995bd199784f0c846a1e
Reviewed-on: https://chromium-review.googlesource.com/1134046
Reviewed-by: Eugene But <eugenebut@chromium.org>
Commit-Queue: Danyao Wang <danyao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574367}
1 file changed