Fix IOS.RestoreNavigationItemCount histogram name.

Follow up for http://crrev.com/c/1225697/6/ios/web/navigation/navigation_manager_impl.mm#21

R=mpearson@chromium.org

Bug: 877671
Cq-Include-Trybots: luci.chromium.try:ios-simulator-cronet;luci.chromium.try:ios-simulator-full-configs
Change-Id: I390bef0562886d5f02469a184ddb6c86f3f62563
Reviewed-on: https://chromium-review.googlesource.com/1229617
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592178}
2 files changed