
The purpose of ChangeCache is to resolve a project name to a list of changes. This is a natural location for the scanChanges implementation we added to SiteIndexer. However, most users in a running server will still just want use the secondary index lookup, as it's faster. So we extract an interface and provide two implementations. Change-Id: I66c24b337cdc6aa787f450f8e0b2dfa17b0cdf97