DM: add --key and --properties to PNG description field.

DM: add --key and --properties to PNG description field.

This tags each image with the bot that created it.

BUG=skia:4322
Committed: https://skia.googlesource.com/skia/+/d69ece6a03d497cead8dc5c5ea2d682e49800df4

[mtklein_C, 2015-09-10 15:08:22]

mtklein@chromium.org changed reviewers:
+ stephana@google.com

[mtklein_C, 2015-09-10 15:08:25]

The CQ bit was checked by mtklein@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-09-10 15:08:34]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1332903002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1332903002/1

[commit-bot: I haz the power, 2015-09-10 15:13:08]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-09-10 15:13:08]

Dry run: This issue passed the CQ dry run.

[stephana, 2015-09-10 16:28:24]

On 2015/09/10 15:13:08, commit-bot: I haz the power wrote:
> Dry run: This issue passed the CQ dry run.

lgtm

[mtklein, 2015-09-10 17:37:01]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2015-09-10 17:37:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1332903002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1332903002/1

[commit-bot: I haz the power, 2015-09-10 17:37:49]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/d69ece6a03d497cead8dc5c5ea2d682e49800df4