Update VPD cache file location.

chromeos/system/statistics_provider.cc

Index: chromeos/system/statistics_provider.cc
diff --git a/chromeos/system/statistics_provider.cc b/chromeos/system/statistics_provider.cc
index c7144df5196d5af893341892cb124def354a3600..adfd9c862ef1104030bba2a8e5c391d443cc3814 100644
--- a/chromeos/system/statistics_provider.cc
+++ b/chromeos/system/statistics_provider.cc
@@ -57,7 +57,8 @@ const char kMachineHardwareInfoDelim[] = " \n";
 
 // File to get ECHO coupon info from, and key/value delimiters of
 // the file.
-const char kEchoCouponFile[] = "/var/cache/echo/vpd_echo.txt";
+const char kEchoCouponFile[] =
+    "/mnt/stateful_partition/unencrypted/cache/vpd/echo/vpd_echo.txt";
 const char kEchoCouponEq[] = "=";
 const char kEchoCouponDelim[] = "\n";