make a shallow-copy so we don't get racy trying to lock/unlock our private bitmap

make a shallow-copy so we don't get racy trying to lock/unlock our private bitmap

BUG=529995
NOTREECHECKS=True

Committed: https://skia.googlesource.com/skia/+/a10bb86da82449b8756da5d00384993351f56d1d

[reed1, 2015-09-10 18:30:05]

reed@google.com changed reviewers:
+ fmalita@chromium.org, robertphillips@google.com

[reed1, 2015-09-10 18:30:05]

PTAL

[reed1, 2015-09-10 18:30:47]

The CQ bit was checked by reed@google.com to run a CQ dry run

[commit-bot: I haz the power, 2015-09-10 18:30:58]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1327313002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1327313002/1

[robertphillips, 2015-09-10 18:36:03]

lgtm

[f(malita), 2015-09-10 18:36:37]

LGTM

Nit: can you link to the chromium bug?

https://codereview.chromium.org/1327313002/diff/1/src/image/SkImage_Raster.cpp
File src/image/SkImage_Raster.cpp (right):

https://codereview.chromium.org/1327313002/diff/1/src/image/SkImage_Raster.cp...
src/image/SkImage_Raster.cpp:172: localShallowCopy.unlockPixels();
This may solve the preRoll race, but don't we have the same issue when drawing
the same SkImage on multiple threads?  I presume internally we still call
lock/unlock on fBitmap in that case.

[reed1, 2015-09-10 18:37:49]

The CQ bit was unchecked by reed@google.com

[reed1, 2015-09-10 18:37:52]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2015-09-10 18:37:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1327313002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1327313002/1

[commit-bot: I haz the power, 2015-09-10 18:39:01]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/a10bb86da82449b8756da5d00384993351f56d1d

[reed1, 2015-09-10 18:40:06]

Other methods area already safe (also my making shallow copies):

- getROPixels() returns a copy
- onReadPixels() makes a shallowCopy