simplify uniqueID code in picture

simplify uniqueID code in picture

patch from issue 750003002 at patchset 1 (http://crrev.com/750003002#ps1)

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/41d2c2e434d11e73f66c597913c29ea1fb3fa879

[reed1, 2014-11-21 15:42:18]

reed@google.com changed reviewers:
+ mtklein@google.com, robertphillips@google.com

[reed1, 2014-11-21 15:42:18]

clone of the prev patch -- will update dox

[reed1, 2014-11-21 15:44:34]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2014-11-21 15:45:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/752573002/20001

[commit-bot: I haz the power, 2014-11-21 15:45:18]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2014-11-21 21:45 UTC

[mtklein, 2014-11-21 15:51:56]

https://codereview.chromium.org/752573002/diff/20001/src/core/SkPicture.cpp
File src/core/SkPicture.cpp (right):

https://codereview.chromium.org/752573002/diff/20001/src/core/SkPicture.cpp#n...
src/core/SkPicture.cpp:48: static int32_t gPictureGenerationID;
If find the loop below less clear without "= SK_InvalidGenID" here.

Or, we can just screw the loop.  We're not mutating pictures, and we're not
making 2 billion pictures either.

[reed1, 2014-11-21 15:54:14]

The CQ bit was unchecked by reed@google.com

[reed1, 2014-11-21 15:55:38]

On 2014/11/21 15:51:56, mtklein wrote:
> https://codereview.chromium.org/752573002/diff/20001/src/core/SkPicture.cpp
> File src/core/SkPicture.cpp (right):
> 
>
https://codereview.chromium.org/752573002/diff/20001/src/core/SkPicture.cpp#n...
> src/core/SkPicture.cpp:48: static int32_t gPictureGenerationID;
> If find the loop below less clear without "= SK_InvalidGenID" here.
> 
> Or, we can just screw the loop.  We're not mutating pictures, and we're not
> making 2 billion pictures either.

Doh, forgot the symbol in the loop. will fix.

Perhaps we can at least create a centralized (private) function that "bumps an
atomic 32 and never returns 0" -- then we can have the debate about the need (or
not) for the loop in one place :)

[reed1, 2014-11-21 15:56:57]

https://codereview.chromium.org/752573002/diff/20001/src/core/SkPicture.cpp
File src/core/SkPicture.cpp (right):

https://codereview.chromium.org/752573002/diff/20001/src/core/SkPicture.cpp#n...
src/core/SkPicture.cpp:48: static int32_t gPictureGenerationID;
On 2014/11/21 15:51:56, mtklein wrote:
> If find the loop below less clear without "= SK_InvalidGenID" here.
> 
> Or, we can just screw the loop.  We're not mutating pictures, and we're not
> making 2 billion pictures either.

Done.

[reed1, 2014-11-21 15:57:00]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2014-11-21 15:57:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/752573002/40001

[commit-bot: I haz the power, 2014-11-21 15:57:32]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2014-11-21 21:57 UTC

[mtklein, 2014-11-21 15:57:46]

lgtm

[commit-bot: I haz the power, 2014-11-21 16:07:46]

Committed patchset #3 (id:40001) as
https://skia.googlesource.com/skia/+/41d2c2e434d11e73f66c597913c29ea1fb3fa879