Uses an enum to describe how many files are expanded:
- NONE
- SOME
- ALL
When NONE:
- Expand all button is visible
- Collapse all button is hidden
- View mode/Settings hidden
When SOME:
- Expand all button is visible
- Collapse all button is hidden
- View mode/Settings are visible
- Selected view mode is highlighted in blue
When ALL:
- Expand all button is hidden
- Collapse all button is visible
- View mode/settings same as 'SOME'
Change-Id: I9c4f1e302ad94de6034b9cbaffffae649f0bc6b8
75a20316bf