Introduce ChromeOS-style keyboard navigation.
- Turn the DirectoryFragment (DF) and the RootsFragment (RF) into
top-level views, and allow switching between them via the tab key.
- Disallow arrow-key navigation from switching the user between the
DF and RF.
- When nothing is explicitly focused, make navigation keys focus the
DF. This makes it so that if a user opens DocumentsUI and just starts
pressing arrow keys, they'll navigate in the directory listing.
- When restoring focus on the DF and RF, remember the last thing that
was focused, and restore focus on that thing.
BUG=25195767
BUG=25121367
Change-Id: I00e20cbdbe9edfe269fb356440a93ef5d67c5298
(cherry picked from commit 1c9f9222e56482682461013b703590c5c9471018)
12 files changed