Re-land "Show snackbar with "undo" when deleting most visited item."

When the user removes a most visited item from the NTP (via long press >
Remove), we now show a snackbar that says:

  [ Item removed    | Undo ]

If the user clicks the Undo button, the most visited item is added back.
Navigating away from the NTP will cause the snackbar to be hidden
immediately.

BUG=368333

Review URL: https://codereview.chromium.org/1587193009

Cr-Commit-Position: refs/heads/master@{#370317}

Review URL: https://codereview.chromium.org/1607233003

Cr-Commit-Position: refs/heads/master@{#370591}
7 files changed