[Chromecast] Move audio logging from PushFrame to Start.

[Chromecast] Move audio logging from PushFrame to Start.

Putting logging in CastAudioOutputStream::PushFrame was generating many
unnecessary tasks. Moving the logging call to Start() greatly reduces
the number of posted tasks and still records the metric properly.

BUG=internal b/23214538

Committed: https://crrev.com/7936d0c4cc3886613a86643aaf411e31a89d0b24
Cr-Commit-Position: refs/heads/master@{#350867}

[mbjorge, 2015-09-25 17:34:06]

mbjorge@chromium.org changed reviewers:
+ alokp@chromium.org, derekjchow@chromium.org, halliwell@chromium.org

[halliwell, 2015-09-25 17:35:45]

On 2015/09/25 17:34:19, mbjorge wrote:

lgtm, send me that bug as well :)

[mbjorge, 2015-09-25 17:54:58]

The CQ bit was checked by mbjorge@chromium.org

[commit-bot: I haz the power, 2015-09-25 17:55:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1365173005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1365173005/1

[commit-bot: I haz the power, 2015-09-25 18:20:18]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-25 18:21:23]

Patchset 1 (id:??) landed as
https://crrev.com/7936d0c4cc3886613a86643aaf411e31a89d0b24
Cr-Commit-Position: refs/heads/master@{#350867}