commit a4acc90b0a0bbfa55ed247a3ae04c766c885d220
author Ben Kwa <kenobi@google.com> Wed Feb 10 15:48:25 2016 -0800
committer Ben Kwa <kenobi@google.com> Thu Feb 18 12:04:35 2016 -0800
tree c7f5cf48931526ced9f53e09adb0d94af0a526b5
parent 21eb4e2684e8490deedab002dd2b867b6d35147a

Implement type-to-focus in the DirectoryFragment.

Add a helper to the FocusManager, to handle alphanumeric keystrokes.
- Build a search index mapping document titles to adapter positions, and
  keep it up-to-date.
- Intercept alphanumeric keystrokes and build up a search string from
  them.
- Use the search string and index to set focus in the directory listing.
- Highlight code is written, but not activated in the UI for now, to
  minimize surface area for potential breakages.  Revisit enabling
  highlights for O.

BUG=24988911

Change-Id: I148ff5583c655338d12bc06d6484a9ed7aa528ad