Remove extra memcpys from AudioPullFifo.

Remove extra memcpys from AudioPullFifo.

Due to AudioPullFifo always clearing the |fifo_| before reading
another block from |read_cb_| we can actually remove the AudioFifo
object in favor of a plain AudioBus.

Speedup is ~17% over the old version per AudioConverter benchmark
using --audio-converter-iterations=500000:
Old: 430.04ms
New: 355.44ms

BUG=none
TEST=media_unittests

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=201662

[no longer working on chromium, 2013-05-20 08:56:00]

Thanks for the improvement. lgtm with one nit.

https://codereview.chromium.org/15394003/diff/1/media/base/audio_pull_fifo.cc
File media/base/audio_pull_fifo.cc (right):

https://codereview.chromium.org/15394003/diff/1/media/base/audio_pull_fifo.cc...
media/base/audio_pull_fifo.cc:52: int frames = std::min(frames_to_provide,
fifo_->frames() - fifo_index_);
nit, it seems it will be quite common for the |frames| to be 0, do an early
return here?

[DaleCurtis, 2013-05-21 23:26:29]

https://codereview.chromium.org/15394003/diff/1/media/base/audio_pull_fifo.cc
File media/base/audio_pull_fifo.cc (right):

https://codereview.chromium.org/15394003/diff/1/media/base/audio_pull_fifo.cc...
media/base/audio_pull_fifo.cc:52: int frames = std::min(frames_to_provide,
fifo_->frames() - fifo_index_);
On 2013/05/20 08:56:00, xians1 wrote:
> nit, it seems it will be quite common for the |frames| to be 0, do an early
> return here?

There's a frames > 0 check on the for() loop, but I admit that's sneaky, so
changed to an explicit check.

[commit-bot: I haz the power, 2013-05-21 23:29:21]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dalecurtis@chromium.org/15394003/5001

[commit-bot: I haz the power, 2013-05-21 23:48:11]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dalecurtis@chromium.org/15394003/19001

[commit-bot: I haz the power, 2013-05-22 08:03:52]

Retried try job too often on win7_aura for step(s) content_browsertests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win7_aura&...

[commit-bot: I haz the power, 2013-05-22 17:37:34]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dalecurtis@chromium.org/15394003/19001

[commit-bot: I haz the power, 2013-05-23 01:32:26]

Change committed as 201662