Add CaptioningManager listener Subtitle support.

Update default track selection based on settings change.
Implement HLS track selection scheme.
This requires synchronization for subtitletrack and controller.

Change-Id: I8295956d264ab2016a83957ace37d9d7b1acde4c
Signed-off-by: Lajos Molnar <lajos@google.com>
Bug: 10326117
5 files changed