Remove comments from the PNG callbacks

Remove comments from the PNG callbacks

The comments and the callback routine names repeat themselves. Retain
the valuable things (the compiler decides the matter).

Also choose names that do help describe pngRowAvailable() but without
introducing concepts like "interlacing" so early in the code: use row
and state instead.

BUG=439655
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=187022

[Noel Gordon, 2014-12-12 05:42:55]

noel@chromium.org changed reviewers:
+ kbr@chromium.org, tkent@chromium.org

[Noel Gordon, 2014-12-12 05:48:12]

Last one in this series, btw.

[Noel Gordon, 2014-12-12 06:06:18]

Patchset #1 (id:1) has been deleted

[Ken Russell (switch to Gerrit), 2014-12-12 06:10:13]

lgtm

[Noel Gordon, 2014-12-12 07:56:45]

The CQ bit was checked by noel@chromium.org

[commit-bot: I haz the power, 2014-12-12 07:57:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/797923002/20001

[commit-bot: I haz the power, 2014-12-12 08:13:45]

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

[commit-bot: I haz the power, 2014-12-12 08:13:46]

Try jobs failed on following builders:
  linux_chromium_gn_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_chromium_gn_rel/bu...)

[Noel Gordon, 2014-12-12 09:14:06]

The CQ bit was checked by noel@chromium.org

[Noel Gordon, 2014-12-12 09:14:07]

The CQ bit was unchecked by noel@chromium.org

[Noel Gordon, 2014-12-12 09:19:00]

The CQ bit was checked by noel@chromium.org

[commit-bot: I haz the power, 2014-12-12 09:20:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/797923002/20001

[Noel Gordon, 2014-12-12 09:20:46]

Tree redness dealt with on https://codereview.chromium.org/797183002

[commit-bot: I haz the power, 2014-12-12 10:59:38]

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

[commit-bot: I haz the power, 2014-12-12 10:59:38]

Try jobs failed on following builders:
  linux_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/3...)

[Noel Gordon, 2014-12-12 12:26:31]

The CQ bit was checked by noel@chromium.org

[commit-bot: I haz the power, 2014-12-12 12:27:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/797923002/20001

[commit-bot: I haz the power, 2014-12-12 13:39:56]

Committed patchset #1 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=187022