Move classes to //components/ntp_tiles.

Move MostVisitedSites and PopularSites; leave behind ChromePopularSites,
which depends on Chrome paths.

In the short term, there are no changes introduced by this CL; the same
code builds as before against the same dependencies. In the future,
multiple platforms' versions of the new tab page will share this part of
their implementation. (Android's NTP currently is all native code; on
other platforms we use HTML)

BUG=603026

Review-Url: https://codereview.chromium.org/1983063002
Cr-Commit-Position: refs/heads/master@{#399455}
19 files changed