Migrating existing code to Clock abstraction part 1

This CL includes the following changes:
  Refactor Clock.java for better readability
  Use Clock abstraction for classes which already have
  a reference of Clock obejct.

BUG=28701686
TEST=compile
TEST=runtest frameworks-wifi

Change-Id: I49e896a91a63cf4519368a9de259046c21c94ddb
14 files changed
tree: 84bb8b52cd4b85fa19ffebbe5e90d4db10107d55
  1. service/
  2. tests/