[Sync] Fix crash in GCP when adding encrypted entry that already exists.

sync/internal_api/public/write_node.h

Index: sync/internal_api/public/write_node.h
diff --git a/sync/internal_api/public/write_node.h b/sync/internal_api/public/write_node.h
index 23e00b84146115c2efe1bd994ef8d1340af312e7..c764766f83f00c659849949e07d21344b1416d99 100644
--- a/sync/internal_api/public/write_node.h
+++ b/sync/internal_api/public/write_node.h
@@ -49,6 +49,8 @@ class SYNC_EXPORT WriteNode : public BaseNode {
     INIT_FAILED_COULD_NOT_CREATE_ENTRY,
     // Setting the predecessor failed
     INIT_FAILED_SET_PREDECESSOR,
+    // Found existing entry, but was unable to decrypt.
+    INIT_FAILED_DECRYPT_EXISTING_ENTRY,
   };
 
   // Create a WriteNode using the given transaction.