Improve ongoing usage dialog.

Fix a bug where the permission icons were not vertically centered.

Migrate the logic from the Activity to a Fragment to support TV.

Fix an issue where if you opened the dialog, followed it to another
screen, went to home, then re-opened the dialog, you would see the old
screen under it.

Test: Open dialog, click various options, re-open dialog.
Change-Id: I2dd1d195d32f8eb141d52c54d14f677f3d0b62bf