libpng: Optimize RGBA png_do_expand_palette

libpng: Optimize RGBA png_do_expand_palette

ARM-specific optimization processes 4 pixels at once via NEON.
Improves performance by at least 10% on large images.

BUG=706134

[cavalcantii1, 2017-03-23 19:39:15]

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

[commit-bot: I haz the power, 2017-03-23 19:39:42]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-23 20:10:26]

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

[commit-bot: I haz the power, 2017-03-23 20:10:27]

Dry run: Try jobs failed on following builders:
  linux_chromium_chromeos_ozone_rel_ng on master.tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[cavalcantii1, 2017-03-23 21:30:37]

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

[commit-bot: I haz the power, 2017-03-23 21:31:22]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-23 22:42:22]

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

[commit-bot: I haz the power, 2017-03-23 22:42:22]

Dry run: Try jobs failed on following builders:
  linux_chromium_chromeos_ozone_rel_ng on master.tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[cavalcantii1, 2017-03-27 17:32:16]

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

[commit-bot: I haz the power, 2017-03-27 17:33:42]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-27 19:27:56]

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

[commit-bot: I haz the power, 2017-03-27 19:27:57]

Dry run: This issue passed the CQ dry run.

[richard.townsend, 2017-03-28 20:32:50]

Description was changed from

==========
libpng: Optimize RGBA png_do_expand_palette

ARM-specific optimization processes 4 pixels at once via NEON.
Improves performance by at least 10% on large images.

BUG=
==========

to

==========
libpng: Optimize RGBA png_do_expand_palette

ARM-specific optimization processes 4 pixels at once via NEON.
Improves performance by at least 10% on large images.

BUG=706134
==========

[cavalcantii1, 2017-03-28 22:14:26]

On 2017/03/28 22:11:21, cavalcantii1 wrote:

The idea now is to contact libpng developers and upstream this optimization so
that Chromium can sync with libpng in a later release.