Remove png_read_end from SkPngScanlineDecoder

removing png_read_end from SkPngScanlineDecoder

BUG=skia:4041
Committed: https://skia.googlesource.com/skia/+/973ae86a824c6c1ece428d6777d0bce648f3f20c

[scroggo, 2015-07-20 20:07:25]

scroggo@google.com changed reviewers:
+ scroggo@google.com

[scroggo, 2015-07-20 20:07:26]

Not sure whether you intended to send this out for review, but it LGTM as-is, or
with some small fixes.

> removing png_read_end from SkPngScanlineDecoder

nit: According to https://git-scm.com/book/ch5-2.html:

> It’s also a good idea to use the imperative present tense
> in these messages. In other words, use commands. Instead of
> “I added tests for” or “Adding tests for,” use “Add tests
> for.”

Following those conventions, the title would be:

Remove png_read_end from SkPngScanlineDecoder

That said, we do not have a recommendation within Skia, and not everyone writes
their messages the same way, so no need to do it just because I say so.

https://codereview.chromium.org/1242423002/diff/1/src/codec/SkCodec_libpng.cpp
File src/codec/SkCodec_libpng.cpp (right):

https://codereview.chromium.org/1242423002/diff/1/src/codec/SkCodec_libpng.cp...
src/codec/SkCodec_libpng.cpp:604: ~SkPngScanlineDecoder() {}
nit: I think you can remove this line completely, and the compiler will generate
the same destructor.

(I was wrong on this in one of Matt's CLs, so I may be wrong here as well...)

https://codereview.chromium.org/1242423002/diff/1/src/codec/SkCodec_libpng.cp...
src/codec/SkCodec_libpng.cpp:663: ~SkPngInterlacedScanlineDecoder() {}
Again, I *think* the compiler will generate the same destructor without this
line.

[emmaleer, 2015-07-20 20:30:56]

The CQ bit was checked by emmaleer@google.com

[emmaleer, 2015-07-20 20:30:57]

The patchset sent to the CQ was uploaded after l-g-t-m from scroggo@google.com
Link to the patchset: https://codereview.chromium.org/1242423002/#ps20001
(title: "Remove finish() function from SkPngCodec")

[commit-bot: I haz the power, 2015-07-20 20:31:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1242423002/20001

[commit-bot: I haz the power, 2015-07-20 20:38:50]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/973ae86a824c6c1ece428d6777d0bce648f3f20c