Since TrafficStats is moving into the mainline module,
ServiceManager#getService can no longer be accessed.
This change use reflection to access getService, since
there is no offical way to get the service binder,
and TrafficStats is a static utility that doesn't have
the context to invoke Context#getSystemService.
This change also fixes minor lint errors.
Test: atest CtsNetTestCases:TrafficStatsTest
Bug: 204830222
Change-Id: I5caec42a71431b39f747fc791b8511d92e5cf7cc
DataUnit is a hidden class, remove the references to
it from files that about to be moved into the module.
Test: TH
Bug: 204830222
Change-Id: Ibfb82ab74f283686fb2af6c3a550d541440c890d
NetworkStatsService is going to be moved into ConnectivityService
module. Move all related files to packages/ConnectivityT so that
it can be easily migrate these files to connectivity module
after clearing the hidden API usages.
Bug: 197717846
Test: TH
Change-Id: Iead00832b5eb7b1dc40a92027c5a14ae8316b16c
