Add jpeg_skip_scanlines() API to libjpeg-turbo

Add jpeg_skip_scanlines() API to libjpeg-turbo

jpeg_skip_scanlines() API, a subset decoding optimization
aimed at Android, was submitted upstream r1582. Pull that
change, and sundry fixes, into the Chromium repo.

This new API is targetted at Android devices, not Chrome,
and should have no affect on JPEG decode behavior or perf
of Chrome.

Chrome uses suspending data source JPEG decoding, and the
new API does not support such sources. Adding support for
suspending data sources is a future TODO, should the need
arise (refer to skbug.com/4036).

BUG=515694

[msarett, 2015-07-28 18:06:58]

Patchset #1 (id:1) has been deleted

[msarett, 2015-07-28 18:18:28]

msarett@google.com changed reviewers:
+ djsollen@google.com, noel@google.com, scroggo@google.com

[Noel Gordon, 2015-07-29 13:29:15]

I assume this is the upstream patch contributed by google, as in a cherry-pick
of it?  You should read the README.chromium file and add the required details
about the source of the patch therein, and include the README.chromium in this
patch.

[msarett, 2015-07-29 14:20:27]

Yes of course!  Looks like I missed that.

[Noel Gordon, 2015-07-30 19:10:06]

noel@chromium.org changed reviewers:
+ noel@chromium.org

[Noel Gordon, 2015-07-30 19:10:07]

https://codereview.chromium.org/1258673007/diff/40001/README.chromium
File README.chromium (right):

https://codereview.chromium.org/1258673007/diff/40001/README.chromium#newcode34
README.chromium:34: * Removed .func / .endfunc lines from arm assembly
Not your issue, but lines 34-36 can be removed while we are here. r1375 has been
cherry picked (see line 14).

https://codereview.chromium.org/1258673007/diff/40001/README.chromium#newcode44
README.chromium:44: The 'google.patch' file represents our changes from the
original
And we update it with every change (refer to other changes via % git log -- .)
and creating it is an exercise in git and/or git svn foo.

https://codereview.chromium.org/1258673007/diff/40001/README.chromium#newcode51
README.chromium:51: [1]
https://www.chromium.org/developers/how-tos/get-the-code/working-with-nested-...
I assume you are using these instructions. agable@ recently updated them, you
are our first test driver.

[msarett, 2015-07-30 20:07:31]

Patchset #3 (id:60001) has been deleted

[msarett, 2015-07-30 20:16:52]

https://codereview.chromium.org/1258673007/diff/40001/README.chromium
File README.chromium (right):

https://codereview.chromium.org/1258673007/diff/40001/README.chromium#newcode34
README.chromium:34: * Removed .func / .endfunc lines from arm assembly
On 2015/07/30 19:10:06, noel gordon wrote:
> Not your issue, but lines 34-36 can be removed while we are here. r1375 has
been
> cherry picked (see line 14).

Done.

https://codereview.chromium.org/1258673007/diff/40001/README.chromium#newcode44
README.chromium:44: The 'google.patch' file represents our changes from the
original
On 2015/07/30 19:10:07, noel gordon wrote:
> And we update it with every change (refer to other changes via % git log -- .)
> and creating it is an exercise in git and/or git svn foo.

I did the following:
1) Download libjpeg-turbo at svn revision 829.
2) Overwrote all of the files with my current local copy of libjpeg-turbo.
3) Did: svn diff > google.patch

The output is a little surprising because it's not too similar to the old
google.patch file.  Did I do something wrong?  Or maybe I should omit some files
from the diff (bmp.c, README, etc)?  Or maybe the old google.patch file was out
of date?

Let me know what you think.

https://codereview.chromium.org/1258673007/diff/40001/README.chromium#newcode51
README.chromium:51: [1]
https://www.chromium.org/developers/how-tos/get-the-code/working-with-nested-...
On 2015/07/30 19:10:07, noel gordon wrote:
> I assume you are using these instructions. agable@ recently updated them, you
> are our first test driver.

All I did was:
git checkout master
git checkout -t -b working-branch master
// Made local changes
git commit -a -m "bla"
git cl upload

It looks like that doesn't quite follow the steps, so I'll be sure to backtrack
and do things the right way.

[Noel Gordon, 2015-07-30 22:25:02]

On 2015/07/30 20:16:52, msarett wrote:
> https://codereview.chromium.org/1258673007/diff/40001/README.chromium
> File README.chromium (right):
> 
>
https://codereview.chromium.org/1258673007/diff/40001/README.chromium#newcode34
> README.chromium:34: * Removed .func / .endfunc lines from arm assembly
> On 2015/07/30 19:10:06, noel gordon wrote:
> > Not your issue, but lines 34-36 can be removed while we are here. r1375 has
> been
> > cherry picked (see line 14).
> 
> Done.
> 
>
https://codereview.chromium.org/1258673007/diff/40001/README.chromium#newcode44
> README.chromium:44: The 'google.patch' file represents our changes from the
> original
> On 2015/07/30 19:10:07, noel gordon wrote:
> > And we update it with every change (refer to other changes via % git log --
.)
> > and creating it is an exercise in git and/or git svn foo.
> 
> I did the following:
> 1) Download libjpeg-turbo at svn revision 829.
> 2) Overwrote all of the files with my current local copy of libjpeg-turbo.
> 3) Did: svn diff > google.patch
> 
> The output is a little surprising because it's not too similar to the old
> google.patch file.  Did I do something wrong?  Or maybe I should omit some
files
> from the diff (bmp.c, README, etc)?  Or maybe the old google.patch file was
out
> of date?
> 
> Let me know what you think.

Yes, you should only include the files you changed.  On the other hand, I think
that google.patch has become a burden.  There is a simple way to compute it, but
it is simply non-obvious.  One option is we get rid of it, and better document
our changes using bugs etc in the README.chromium file.

Second thing, I was not able to edit your change on the new issue, and it needs
some edits, so I did those here.  Could you copy them over to your new review
issue, please?

[Noel Gordon, 2015-07-31 16:01:23]

Work was completed on another issue, closing this one (so it's off my queue).

[Noel Gordon, 2015-07-31 16:11:50]

On 2015/07/31 16:01:23, noel gordon wrote:
> Work was completed on another issue, closing this one (so it's off my queue).

https://codereview.appspot.com/256280043 for the record.