Make checkpointing work on ext4

Test: All tests pass
Change-Id: I2a6cdf1edfe752f4633e1931e75d18659653938c
diff --git a/binder/android/os/IVold.aidl b/binder/android/os/IVold.aidl
index fd97077..f4458a8 100644
--- a/binder/android/os/IVold.aidl
+++ b/binder/android/os/IVold.aidl
@@ -101,6 +101,7 @@
     void abortChanges();
     boolean commitChanges();
     boolean prepareDriveForCheckpoint(@utf8InCpp String mountPoint);
+    boolean restoreCheckpoint(@utf8InCpp String device);
     boolean markBootAttempt();
 
     const int ENCRYPTION_FLAG_NO_UI = 4;