am 997dc32b: Merge "add an api for getting a device serial number" into gingerbread

Merge commit '997dc32b6bef1c9cc8ac6d4d598698507b2c4934' into gingerbread-plus-aosp

* commit '997dc32b6bef1c9cc8ac6d4d598698507b2c4934':
  add an api for getting a device serial number