Modifies AudioInputCallback::OnData and use media::AudioBus instead of plain byte vector (Relanding)

Modifies AudioInputCallback::OnData and use media::AudioBus instead of plain byte vector (Relanding).

Second attempt to land https://codereview.chromium.org/314713002/ which has been reverted.

TBR=dalecurtis
BUG=375155
TEST=WebRTC and WebSpeech demos

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=278345

[henrika (OOO until Aug 14), 2014-06-19 12:39:27]

Committed patchset #4 manually as r278345 (presubmit successful).

[no longer working on chromium, 2014-06-19 12:46:50]

On 2014/06/19 12:39:27, henrika (OOO June 23-July 7) wrote:
> Committed patchset #4 manually as r278345 (presubmit successful).

lgtm and thanks for the offline explaination :) hope it stays.