DO NOT MERGE: Refactored NetworkStatsServiceTest to use Mockito instead of EasyMock. am: e4c029918f  -s ours am: fbbaf25665  -s ours am: a20ccdb0ab
am: a2c40b19c6  -s ours

Change-Id: Ic3005458ec91655ce105c70569877cf5dd8a920b