SkOnce for SkXfermode::Create(Mode)

SkOnce for SkXfermode::Create(Mode)

This removes the mutex from the fast path when we've already cached it.

BUG=skia:

Committed: http://code.google.com/p/skia/source/detail?r=13986

[bungeman-skia, 2014-03-28 18:08:07]

https://codereview.chromium.org/215533002/diff/1/src/core/SkXfermode.cpp
File src/core/SkXfermode.cpp (left):

https://codereview.chromium.org/215533002/diff/1/src/core/SkXfermode.cpp#oldc...
src/core/SkXfermode.cpp:1699: // so we can just return NULL from the factory.
nit: Really? Removing a period at the end of an actual sentence? When there's
already a period at the end of the previous sentence? Oh, the punctuation!

[mtklein, 2014-03-28 18:08:43]

https://codereview.chromium.org/215533002/diff/1/src/core/SkXfermode.cpp
File src/core/SkXfermode.cpp (left):

https://codereview.chromium.org/215533002/diff/1/src/core/SkXfermode.cpp#oldc...
src/core/SkXfermode.cpp:1699: // so we can just return NULL from the factory.
On 2014/03/28 18:08:08, bungeman1 wrote:
> nit: Really? Removing a period at the end of an actual sentence? When there's
> already a period at the end of the previous sentence? Oh, the punctuation!

oooops, done.

[mtklein, 2014-03-28 18:08:47]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2014-03-28 18:09:05]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/mtklein@chromium.org/215533002/20001

[commit-bot: I haz the power, 2014-03-28 18:09:07]

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

[commit-bot: I haz the power, 2014-03-28 18:09:07]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer or
a lowly provisional committer, _not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[bungeman-skia, 2014-03-28 18:11:03]

lgtm

[mtklein, 2014-03-28 18:11:07]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2014-03-28 18:11:15]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/mtklein@chromium.org/215533002/20001

[mtklein, 2014-03-28 19:30:10]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2014-03-28 19:30:13]

CQ is trying da patch. Follow status at
https://skia-tree-status.appspot.com/cq/mtklein@chromium.org/215533002/30001

[commit-bot: I haz the power, 2014-03-28 20:04:23]

Change committed as 13986