[CRD iOS] Remove old audio playback code

This CL removes old audio playback code that is no longer in used.

Bug: 868088
Change-Id: I0dc350fc6d7fcabe89c6c7deba1da34fe53c3667
Reviewed-on: https://chromium-review.googlesource.com/1171855
Reviewed-by: Joe Downing <joedow@chromium.org>
Commit-Queue: Yuwei Huang <yuweih@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583340}
13 files changed