Use "Product_S/N" as the machine id.

Test: Run "sudo dump_vpd_log --full --stdout" on lumpy, daisy,
      this command shows Product_S/N field and it remain unchanged across
      different images.

PRESUBMIT=passed
R=asharif,llozano,shenhan
APPROVED=shenhan
DELTA=2 (0 added, 0 deleted, 2 changed)
OCL=43574435


P4 change: 43788275
1 file changed
tree: 8259f9162e3053593c4fd65bf4a2dc00bae73fc3
  1. .git5_specs/
  2. v14/