Clean up SkOnce:

Clean up SkOnce:

  1 Remove atExit feature: clients can do it just as well as SkOnce can.
  2 Remove support for functors: no one but the unit test did that.
  3 Remove support for unused non-static SkOnceFlag (no SK_ONCE_INIT).
  4 Add SkOnce variants for no-arg functions so we're not forced to pass dummy values all the time.
  5 Merge SkSpinlock and SkOnceFlag, making all members private.
  6 More notes about memory barriers, adding an acquire load after acquiring the spinlock.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/1b81877880253c75f835eede9a8ee21b9e7b584a

[bungeman-skia, 2014-05-30 21:13:18]

lgtm with one nit

https://codereview.chromium.org/302083003/diff/1/include/core/SkOnce.h
File include/core/SkOnce.h (right):

https://codereview.chromium.org/302083003/diff/1/include/core/SkOnce.h#newcod...
include/core/SkOnce.h:131: static void no_arg_adaptor(void (*f)()) {
Can the name be hidden so that 'no_arg_adaptor' doesn't end up being defined at
the top level of the compilation unit? Maybe 'sk_once_no_arg_adaptor' or a
namespace or something.

[mtklein, 2014-06-02 16:11:38]

https://codereview.chromium.org/302083003/diff/1/include/core/SkOnce.h
File include/core/SkOnce.h (right):

https://codereview.chromium.org/302083003/diff/1/include/core/SkOnce.h#newcod...
include/core/SkOnce.h:131: static void no_arg_adaptor(void (*f)()) {
On 2014/05/30 21:13:18, bungeman1 wrote:
> Can the name be hidden so that 'no_arg_adaptor' doesn't end up being defined
at
> the top level of the compilation unit? Maybe 'sk_once_no_arg_adaptor' or a
> namespace or something.

Done.

[mtklein, 2014-06-02 16:14:36]

+reed

Mike, can you take a look for include/ ?  This is a bunch of little changes to
reduce the feature surface of SkOnce now that most things are using SkLazyPtr.

[reed1, 2014-06-02 18:20:10]

include lgtm

[mtklein, 2014-06-02 18:21:46]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2014-06-02 18:22:14]

CQ is trying da patch. Follow status at
 https://skia-tree-status.appspot.com/cq/mtklein@chromium.org/302083003/40001

[commit-bot: I haz the power, 2014-06-02 18:27:04]

Change committed as 1b81877880253c75f835eede9a8ee21b9e7b584a