cros: restore AutomatedVolumeChangeReason in CrasAudioHandler

changes:
The old logic in https://codereview.chromium.org/2250963003 seems
causing problem now, described in crbug.com/777463. We need to
reconsider the solution for crbug.com/625222.

[email protected], [email protected]

Bug: 777463, 712072
Test: test that crbug.com/777463 is fixed.
Change-Id: I7f4a83896febaf05c74a83caf14afeb02b8758ac
Reviewed-on: https://chromium-review.googlesource.com/742390
Commit-Queue: Qiang(Joe) Xu <[email protected]>
Reviewed-by: Qiang(Joe) Xu <[email protected]>
Cr-Commit-Position: refs/heads/master@{#512389}
2 files changed