[iOS] keyboard commands

Added keyboard command:
Command + ← and Command + → should triggered backward and forward
history buttons on chrome app.

Bug: 840662
Change-Id: I749428a6dd0cb8ebc33cc4fc60b6285ea31421af
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1505935
Reviewed-by: Mark Cogan <marq@chromium.org>
Commit-Queue: Nazerke Kalidolda <nazerke@google.com>
Auto-Submit: Nazerke Kalidolda <nazerke@google.com>
Cr-Commit-Position: refs/heads/master@{#641211}
9 files changed