Make ClearAllContentSettingsRules() clear resource IDs as well.
This means that if a resource identifier rule (e.g. plugin allowed on a site) is delete in an old instance of Chrome, the deletion will not propagate to a new version.
This change also affects ProfileResetter, which calls this function to delete all content settings rules; it did not delete rules with resource identifier before.
Since the OriginIdentifierValueMap now only contains one content type per instance, we can delete all rules (regardless of resource identifier) by simply calling clear(), which greatly improves the deletion speed as well.
BUG=475951
Review URL: https://codereview.chromium.org/
1079133003
Cr-Commit-Position: refs/heads/master@{#325022}