AI 147564: Merge back from search branch to donut. Notes:

  - all public apis and framework changes have been reviewed by relevant folks in our branch (e.g romainguy)
  - all new public apis are @hidden; they will still get reviewed by api council once we're in git
  - other than that, it's mostly GlobalSearch and search dialog stuff, a new apps provider, and some tweaks
  to the contacts provider that was reviewed by jham

Automated import of CL 147564