Add workaround for multisampling color masks for the command buffer.

Add workaround for multisampling color masks for the command buffer.

On old AMD GPUs on macOS, glColorMask doesn't work correctly for
multisampled renderbuffers and the alpha channel can be overwritten. This
workaround clears the alpha channel before resolving.

BUG=602484
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_optional_gpu_tests_rel;tryserver.chromium.mac:mac_optional_gpu_tests_rel;tryserver.chromium.win:win_optional_gpu_tests_rel

Committed: https://crrev.com/d4e64fc3153e756b8a1398b8d9dba4f220df6e49
Cr-Commit-Position: refs/heads/master@{#404223}

[erikchen, 2016-07-07 00:13:20]

Description was changed from

==========
Add workaround for multisampling color masks for the command buffer.

On old AMD GPUs on macOS, glColorMask doesn't work correctly for
multisampled renderbuffers and the alpha channel can be overwritten. This
workaround clears the alpha channel before resolving.

BUG=602484
==========

to

==========
Add workaround for multisampling color masks for the command buffer.

On old AMD GPUs on macOS, glColorMask doesn't work correctly for
multisampled renderbuffers and the alpha channel can be overwritten. This
workaround clears the alpha channel before resolving.

BUG=602484
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_optional_gpu_tests_rel;tryserver.chromium.mac:mac_optional_gpu_tests_rel;tryserver.chromium.win:win_optional_gpu_tests_rel
==========

[erikchen, 2016-07-07 00:16:04]

erikchen@chromium.org changed reviewers:
+ piman@chromium.org

[erikchen, 2016-07-07 00:16:04]

piman: Please review.

The test GLNativeGMBTest.TestNativeGMBBackbufferWithDifferentConfigurations
correctly discerns between the existence (or lack thereof) of the workaround.
This hasn't been failing the bots because none of them use this particular GPU.

[erikchen, 2016-07-07 00:16:09]

The CQ bit was checked by erikchen@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-07-07 00:16:55]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[piman, 2016-07-07 00:19:36]

lgtm

[commit-bot: I haz the power, 2016-07-07 03:07:07]

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

[commit-bot: I haz the power, 2016-07-07 03:07:08]

Dry run: Try jobs failed on following builders:
  mac_optional_gpu_tests_rel on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_optional_gpu_...)

[erikchen, 2016-07-07 15:29:54]

The CQ bit was checked by erikchen@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-07-07 15:30:22]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-07 17:34:11]

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

[commit-bot: I haz the power, 2016-07-07 17:34:12]

Dry run: Try jobs failed on following builders:
  chromium_presubmit on master.tryserver.chromium.linux (JOB_TIMED_OUT, no build
URL)
  linux_chromium_rel_ng on master.tryserver.chromium.linux (JOB_TIMED_OUT, no
build URL)

[erikchen, 2016-07-07 19:58:18]

The CQ bit was checked by erikchen@chromium.org

[commit-bot: I haz the power, 2016-07-07 19:58:59]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-07 20:04:59]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-07-07 20:05:17]

CQ bit was unchecked.

[commit-bot: I haz the power, 2016-07-07 20:06:44]

Description was changed from

==========
Add workaround for multisampling color masks for the command buffer.

On old AMD GPUs on macOS, glColorMask doesn't work correctly for
multisampled renderbuffers and the alpha channel can be overwritten. This
workaround clears the alpha channel before resolving.

BUG=602484
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_optional_gpu_tests_rel;tryserver.chromium.mac:mac_optional_gpu_tests_rel;tryserver.chromium.win:win_optional_gpu_tests_rel
==========

to

==========
Add workaround for multisampling color masks for the command buffer.

On old AMD GPUs on macOS, glColorMask doesn't work correctly for
multisampled renderbuffers and the alpha channel can be overwritten. This
workaround clears the alpha channel before resolving.

BUG=602484
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_optional_gpu_tests_rel;tryserver.chromium.mac:mac_optional_gpu_tests_rel;tryserver.chromium.win:win_optional_gpu_tests_rel

Committed: https://crrev.com/d4e64fc3153e756b8a1398b8d9dba4f220df6e49
Cr-Commit-Position: refs/heads/master@{#404223}
==========

[commit-bot: I haz the power, 2016-07-07 20:06:46]

Patchset 1 (id:??) landed as
https://crrev.com/d4e64fc3153e756b8a1398b8d9dba4f220df6e49
Cr-Commit-Position: refs/heads/master@{#404223}