Disable the ALLOW value for camera and mic content settings.
We used to use
MEDIASTREAM content setting for media default ( ASK / BLOCK )
CAMERA / MIC content settings for media exceptions ( ALLOW / ASK / BLOCK )
When we stopped using MEDIASTREAM and replaced it with CAMERA / MIC for defaults as well, we didn't ensure that the ALLOW value is still unsupported as default.
This CL fixes that. Although during the short period when the default settings supported ALLOW values we had no UI to set it, we include a migration code just to be on the safe side.
BUG=464382
Review URL: https://codereview.chromium.org/
1092743005
Cr-Commit-Position: refs/heads/master@{#326486}