GitLab

- Adds NTP_REALBOX page classification to BaseSearchProvider::IsNTPPage()
  and makes it a public static method to use in AutocompleteResult.
- Makes the logic to fall back to most visited site for zero suggest
  mobile only as there are currently no zero suggest experiments on
  Desktop and CrOS is handled differently.

Bug: 996516
Change-Id: I25c33ea961a0afb53abe33f3326696160c6dc3f9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1767605
Commit-Queue: Moe Ahmadi <mahmadi@chromium.org>
Reviewed-by: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#689996}