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The search provider, home page and start pages override permission
messages each take a parameter describing the URL that the setting
can be changed to. This was being properly handed in
settings_override_permission.cc but not in the message formatters in
chrome_permission_message_rules.cc.

This change also removes the duplicate rules for these permissions.

BUG=496332

Review URL: https://codereview.chromium.org/1165553008

Cr-Commit-Position: refs/heads/master@{#333119}