Erase PST partition if its marked to be erased.

We need to wipe the challenges on this partition
if OEM unlock is enabled, as this is a signal that
the user has opted out of factory reset protection.

go/factory-reset

Bug: 16633064
Change-Id: Icb8f1433bf99ca57813f5b72d5a3dd15fa94a263
diff --git a/roots.h b/roots.h
index 230d9de..b62a5b1 100644
--- a/roots.h
+++ b/roots.h
@@ -46,6 +46,11 @@
 // mounted (/tmp and /cache) are mounted.  Returns 0 on success.
 int setup_install_mounts();
 
+// Conditionally wipes the /persistent partition if it's marked
+// to wipe. Returns -1 on failure, 1 if the partition was wiped
+// and 0 if the partition was not wiped.
+int erase_persistent_partition();
+
 #ifdef __cplusplus
 }
 #endif