Revert "update_engine: Update libchrome APIS to r456626."

This reverts commit 663ff4b30b9f629a130ef6d357d462b897d4071e.

Reason for revert: Broke the mac_sdk
Exempt-From-Owner-Approval: Fixing mac_sdk

Change-Id: I8184ec58e74d62dca0deafb39340d4bd36bf40e0
diff --git a/common/test_utils.cc b/common/test_utils.cc
index 3447cdc..fb22c80 100644
--- a/common/test_utils.cc
+++ b/common/test_utils.cc
@@ -248,7 +248,7 @@
                                      string* mnt_path,
                                      unsigned long flags) {  // NOLINT - long
   EXPECT_TRUE(temp_dir_.CreateUniqueTempDir());
-  *mnt_path = temp_dir_.GetPath().value();
+  *mnt_path = temp_dir_.path().value();
 
   string loop_dev;
   loop_binder_.reset(