NewTabPage.LoadTime histograms: Add splits for .Google vs .Other

Semi-related cleanup: Merge the DefaultSearchProviderIsGoogle
implementations between search.cc and local_ntp_source.cc.

Bug: 583292
Change-Id: I47f0a2b1eeb2dfd6e117e81b332a44f09b7e8ee8
Reviewed-on: https://chromium-review.googlesource.com/527437
Reviewed-by: Chris Pickel <sfiera@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#478672}
7 files changed