Refactor NavigationActionBar to use the default ToolBar background instead of re-desigining it
Follow-on from the discussion at !566 (merged)
Reason for the change
- Combine the 3 toolbars stacked on top of each other into 1 big toolbar
- Drop the custom ToolBar background, and just hide the background on mobile
Test plan
Run in both desktop & mobile mode. Test keyboard navigation still goes top-down and left-to-right. Clicking the search button still expands & contracts the toolbar.