Migrate media output switcher metrics - 1/n

Bug: 172181610
Test: (1) run statsd_testdrive 277, and check the
metric output correctness after content switching.
(2) run statsd_testdrive 90, and check the metric
output correctness after launching the output dialog
via Sound Setting / Volume Rocker / Media Object Chip.
(3) atest MediaOutputControllerTest
(4) atest MediaOutputDialogTest
(5) atest MediaOutputBaseDialogTest

Change-Id: I4094a510b5483a456522da9d0d8a6eee1526f687
Merged-In: I0fea0c59afcb44fc1d22920036107524f221a7be