am 8310b42f: Add javadoc saying that wake locks are ref counted by default.

Merge commit '8310b42fbc086b0f05fc8ef45ac34c7e099c485e' into gingerbread-plus-aosp

* commit '8310b42fbc086b0f05fc8ef45ac34c7e099c485e':
  Add javadoc saying that wake locks are ref counted by default.