Steal a bit from the gen ID instead of managing two atomic values.

Steal a bit from the gen ID instead of managing two atomic values.

This extra atomic bool is hard to think about, and I'm worried about how
updates to fGenerationID and fUniqueGenerationID interlace.  By storing
them in the same int, they can't ever race.

CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu13.10-GCE-NoGPU-x86_64-Release-TSAN-Trybot

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/63d0024cde57eba4f7802fdc4fe49467867f52ba

[mtklein_C, 2015-02-25 16:23:41]

mtklein@chromium.org changed reviewers:
+ reed@google.com

[mtklein, 2015-02-25 16:27:20]

On 2015/02/25 16:23:41, mtklein_C wrote:

Don't look at this yet.  Will need to rebase onto the revert.

[mtklein, 2015-02-25 16:34:15]

On 2015/02/25 16:27:20, mtklein wrote:
> On 2015/02/25 16:23:41, mtklein_C wrote:
> 
> Don't look at this yet.  Will need to rebase onto the revert.

OK to look again.

[reed1, 2015-02-25 16:41:31]

lgtm

https://codereview.chromium.org/955043002/diff/60001/src/core/SkPixelRef.cpp
File src/core/SkPixelRef.cpp (right):

https://codereview.chromium.org/955043002/diff/60001/src/core/SkPixelRef.cpp#...
src/core/SkPixelRef.cpp:125: SkASSERT(!this->genIDIsUnique());
// this is a racy assert

[mtklein, 2015-02-25 16:44:44]

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

[mtklein, 2015-02-25 16:44:45]

https://codereview.chromium.org/955043002/diff/60001/src/core/SkPixelRef.cpp
File src/core/SkPixelRef.cpp (right):

https://codereview.chromium.org/955043002/diff/60001/src/core/SkPixelRef.cpp#...
src/core/SkPixelRef.cpp:125: SkASSERT(!this->genIDIsUnique());
On 2015/02/25 16:41:31, reed1 wrote:
> // this is a racy assert

Done.

[mtklein, 2015-02-25 16:44:48]

The CQ bit was checked by mtklein@google.com

[mtklein, 2015-02-25 16:44:49]

The patchset sent to the CQ was uploaded after l-g-t-m from reed@google.com
Link to the patchset: https://codereview.chromium.org/955043002/#ps80001 (title:
"comment raciness")

[commit-bot: I haz the power, 2015-02-25 16:45:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/955043002/80001

[commit-bot: I haz the power, 2015-02-25 17:11:02]

Committed patchset #5 (id:80001) as
https://skia.googlesource.com/skia/+/63d0024cde57eba4f7802fdc4fe49467867f52ba