focus-mode: Finalize the text and tooltip for offline state

This CL will finalize the text and tooltip for the task view and sounds
view when it's offline.

Bug: b/288975135
Test: Manual
Change-Id: I22ad3efd84f3d29712a638c6e80b8032771cd93a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5608914


Commit-Queue: Hongyu Long <hongyulong@chromium.org>
Reviewed-by: Richard Chui <richui@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1312375}