Centralize the audio logic to a new class InputFlowWithAudio

Not every InputFlow supports audio, e.g. VGA. So move the audio specific
logic to a new class InputFlowWithAudio. And HdmiInputFlow inherits this
new class.

TEST=Verified it did not break the existing tests with HDMI interface.

Change-Id: Ic7a2c4db0664c47a9c7f24607a7deae0ade90257
Reviewed-on: https://chromium-review.googlesource.com/227784
Tested-by: Wai-Hong Tam <waihong@chromium.org>
Reviewed-by: Hung-ying Tyan <tyanh@chromium.org>
Commit-Queue: Wai-Hong Tam <waihong@chromium.org>
1 file changed