Extracted the printing page changes from  issue 714350 

We should focus the appropriate subpage arrow after navigating back from a cups printer detail sub page.

The printer details are opened from an action menu, so the best thing might be to focus the corresponding item in the list (this may be tricky, I ran into problems trying to do this for networks) or just focus the list itself (focus will not be visible, but at least 'tab' will do the right thing).

See https://bugs.chromium.org/p/chromium/issues/detail?id=714350#c5 for more details.