Adding an interface to allow extension of the audio player for CRD and iOS.

This CL changes the audio player for CRD into a consumer of audio packets. The choice of consumer is based on a consumer/provider pattern, the intent is to create a new class that will be used in iOS in a following CL that acts as a middle buffer between the CRD Client and the iOS audio player which will extend both AudioConsumer and AudioProvider(not in this CL). Because of this change, I needed the current usage of audio player to extend from a more generic interface (AudioConsumer) which could apply to either this future buffer or audio player.

This is a followup to https://codereview.chromium.org/2052723002, I missed the last upload for the CL changes.

R=sergeyu@chromium.org

BUG=611181

Review-Url: https://codereview.chromium.org/2084123002
Cr-Commit-Position: refs/heads/master@{#401332}
11 files changed