Remove Close All Incognito Tab from TabGrid popup

This CL removes the Close All Incognito Tabs action from the TabGrid
popup menu in incognito, making it the same as the non-incognito.

Bug: 846614
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Ib19301aa9582c7bb2eb94512c50082c40c6dc510
Reviewed-on: https://chromium-review.googlesource.com/1073150
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561851}
4 files changed