sensors: Do not show usage indicator if allowed by default and access was allowed

Change the way we show the usage indicator on the desktop and follow the UX
pattern settings such as cookies and images follow: if we allow by default
and sensors were allowed, do not show the indicator at all.

With this CL, we only show the indicator if:
- We allow by default but access was blocked due to some other reason (e.g.
  the checks in PermissionContextBase::RequestPermission()).
- We block by default but we have a site exception that allows access (so
  the exception can be removed).
- We block by default and access was blocked (due to any reason, including
  any checks from PermissionContextBase::RequestPermission()), in which case
  we offer the option to add a site exception.

Bug: 954131
Change-Id: I10cc828b56d0c37883470187e2d86bc5ebe2d841
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1574806
Commit-Queue: Raphael Kubo da Costa <raphael.kubo.da.costa@intel.com>
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Reviewed-by: Balazs Engedy <engedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653149}
2 files changed