GN: Change libpng to be a group rather than a static_library, since it has no sources.

GN: Change libpng to be a group rather than a static_library, since it has no sources.

BUG=416829
R=brettw@chromium.org

Committed: https://crrev.com/9e2bd7aff70c6ead6e8d66bc370bf61dea076a56
Cr-Commit-Position: refs/heads/master@{#296566}

[Robert Sesek, 2014-09-24 22:28:54]

https://codereview.chromium.org/598233002/diff/1/third_party/libpng/BUILD.gn
File third_party/libpng/BUILD.gn (right):

https://codereview.chromium.org/598233002/diff/1/third_party/libpng/BUILD.gn#...
third_party/libpng/BUILD.gn:73: component("libpng") {
Is it correct to use public_deps with component() like this? If not, I'll change
all OSes to use group().

[brettw, 2014-09-24 22:30:56]

lgtm

https://codereview.chromium.org/598233002/diff/1/third_party/libpng/BUILD.gn
File third_party/libpng/BUILD.gn (right):

https://codereview.chromium.org/598233002/diff/1/third_party/libpng/BUILD.gn#...
third_party/libpng/BUILD.gn:73: component("libpng") {
On 2014/09/24 22:28:54, rsesek wrote:
> Is it correct to use public_deps with component() like this? If not, I'll
change
> all OSes to use group().

Yes, this is fine. An argument could be made that all OS's should just be a
source_set, but this will end up duplicating libpng some number of times and
this matches the GYP build, so I'm inclined to keep it as-is.

[Robert Sesek, 2014-09-24 22:33:22]

The CQ bit was checked by rsesek@chromium.org

[commit-bot: I haz the power, 2014-09-24 22:34:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/598233002/1

[commit-bot: I haz the power, 2014-09-24 23:39:00]

Committed patchset #1 (id:1) as 8dedbfe535a2c5ee41f91bfc15a17b6dbcaa31f2

[commit-bot: I haz the power, 2014-09-24 23:47:10]

Patchset 1 (id:??) landed as
https://crrev.com/9e2bd7aff70c6ead6e8d66bc370bf61dea076a56
Cr-Commit-Position: refs/heads/master@{#296566}