Use SkCanvas transform instead of flipSkImageVertically

Use SkCanvas transform instead of flipSkImageVertically

Currently in ImageBitmap, whenever we need to flip a SkImage, we call the
function flipSkImageVertically, which read the pixels of the SkImage,
swap the pixels and construct a new SkImage from the swapped pixels again.
This process is un-necessary in the case where we already have a SkCanvas
and are drawing to that canvas. In this case, we can just call the
equivalent transformation on SkCanvas to achieve the same flipY effect.

Committed: https://crrev.com/433fb76ec9ee583017b02903c958f0af5a022829
Cr-Commit-Position: refs/heads/master@{#406102}

[xidachen, 2016-07-15 15:06:12]

xidachen@chromium.org changed reviewers:
+ junov@chromium.org

[xidachen, 2016-07-15 15:06:13]

PTAL

[Justin Novosad, 2016-07-18 15:06:49]

Excellent idea

lgtm

[xidachen, 2016-07-18 15:16:39]

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

[commit-bot: I haz the power, 2016-07-18 15:17:01]

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, 2016-07-18 17:52:04]

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

[commit-bot: I haz the power, 2016-07-18 17:52:05]

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

[xidachen, 2016-07-18 18:54:25]

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

[commit-bot: I haz the power, 2016-07-18 18:55:03]

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, 2016-07-18 20:25:04]

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

[commit-bot: I haz the power, 2016-07-18 20:25:05]

Dry run: This issue passed the CQ dry run.

[xidachen, 2016-07-18 21:25:49]

The CQ bit was checked by xidachen@chromium.org

[commit-bot: I haz the power, 2016-07-18 21:26:51]

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, 2016-07-18 21:35:04]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-07-18 21:35:19]

CQ bit was unchecked.

[commit-bot: I haz the power, 2016-07-18 21:37:10]

Description was changed from

==========
Use SkCanvas transform instead of flipSkImageVertically

Currently in ImageBitmap, whenever we need to flip a SkImage, we call the
function flipSkImageVertically, which read the pixels of the SkImage,
swap the pixels and construct a new SkImage from the swapped pixels again.
This process is un-necessary in the case where we already have a SkCanvas
and are drawing to that canvas. In this case, we can just call the
equivalent transformation on SkCanvas to achieve the same flipY effect.
==========

to

==========
Use SkCanvas transform instead of flipSkImageVertically

Currently in ImageBitmap, whenever we need to flip a SkImage, we call the
function flipSkImageVertically, which read the pixels of the SkImage,
swap the pixels and construct a new SkImage from the swapped pixels again.
This process is un-necessary in the case where we already have a SkCanvas
and are drawing to that canvas. In this case, we can just call the
equivalent transformation on SkCanvas to achieve the same flipY effect.

Committed: https://crrev.com/433fb76ec9ee583017b02903c958f0af5a022829
Cr-Commit-Position: refs/heads/master@{#406102}
==========

[commit-bot: I haz the power, 2016-07-18 21:37:11]

Patchset 1 (id:??) landed as
https://crrev.com/433fb76ec9ee583017b02903c958f0af5a022829
Cr-Commit-Position: refs/heads/master@{#406102}