copy-red: Fill an rtc::Buffer with bytes the easy way

copy-red: Fill an rtc::Buffer with bytes the easy way

The easy way also happens to be more efficient if we have to
reallocate, but that's a minor concern here.

Committed: https://crrev.com/81db11aa5031856e0958260c65c36046e832b167
Cr-Commit-Position: refs/heads/master@{#9876}

[kwiberg-webrtc, 2015-09-07 12:47:04]

kwiberg@webrtc.org changed reviewers:
+ henrik.lundin@webrtc.org

[kwiberg-webrtc, 2015-09-07 12:48:06]

𝅘𝅥𝅰

[hlundin-webrtc, 2015-09-07 20:02:44]

lgtm

[kwiberg-webrtc, 2015-09-08 03:13:30]

The CQ bit was checked by kwiberg@webrtc.org

[commit-bot: I haz the power, 2015-09-08 03:13:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1327053002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1327053002/1

[commit-bot: I haz the power, 2015-09-08 03:14:36]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-08 03:14:49]

Patchset 1 (id:??) landed as
https://crrev.com/81db11aa5031856e0958260c65c36046e832b167
Cr-Commit-Position: refs/heads/master@{#9876}