Add foundation for trimming the AffiliationDatabase.

components/password_manager/core/browser/affiliation_backend.h

Index: components/password_manager/core/browser/affiliation_backend.h
diff --git a/components/password_manager/core/browser/affiliation_backend.h b/components/password_manager/core/browser/affiliation_backend.h
index 88dce8d6140201648236445b6115ff95353fa240..a2af115d405ade067bfc82eb62acb6654bbf01de 100644
--- a/components/password_manager/core/browser/affiliation_backend.h
+++ b/components/password_manager/core/browser/affiliation_backend.h
@@ -79,6 +79,10 @@ class AffiliationBackend : public FacetManagerHost,
                       const base::Time& keep_fresh_until);
   void TrimCache();
 
+  // Deletes the cache database file at |db_path|, and all auxiliary files. The
+  // database must be closed before calling this.
+  static void DeleteCache(const base::FilePath& db_path);
+
  private:
   friend class AffiliationBackendTest;