Fix preserve backbuffer with native GMBs.

Fix preserve backbuffer with native GMBs.

The implementation of BackTexture::Copy was using glCopyTexImage2D, which
reallocates storage for the BackTexture. This doesn't work with native GMBs,
since they don't use traditional GL storage mechanisms. Switching to
glCopyTexSubImage2D fixes the problem, and is more efficient since storage has
already been allocated.

BUG=627332
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/2fc766777b27679b88b84561068ef189d550294a
Cr-Commit-Position: refs/heads/master@{#404945}

[erikchen, 2016-07-12 20:41:24]

Description was changed from

==========
Fix preserve backbuffer with native GMBs.
BUG=
==========

to

==========
Fix preserve backbuffer with native GMBs.
BUG=
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, 2016-07-12 20:45:02]

Description was changed from

==========
Fix preserve backbuffer with native GMBs.
BUG=
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

==========
Fix preserve backbuffer with native GMBs.

The implementation of BackTexture::Copy was using glCopyTexImage2D, which
reallocates storage for the BackTexture. This doesn't work with native GMBs,
since they don't use traditional GL storage mechanisms. Switching to
glCopyTexSubImage2D fixes the problem, and is more efficient since storage has
already been allocated.

BUG=627332
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, 2016-07-12 20:45:39]

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

[erikchen, 2016-07-12 20:45:39]

piman: Please review.

[erikchen, 2016-07-12 20:48:42]

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

[commit-bot: I haz the power, 2016-07-12 20:50:59]

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

[piman, 2016-07-12 21:02:50]

lgtm

[erikchen, 2016-07-12 21:03:16]

The CQ bit was unchecked by erikchen@chromium.org

[erikchen, 2016-07-12 21:03:16]

The CQ bit was checked by erikchen@chromium.org

[commit-bot: I haz the power, 2016-07-12 21:06:29]

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, 2016-07-12 22:12:04]

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

[commit-bot: I haz the power, 2016-07-12 22:12:05]

Try jobs failed on following builders:
  linux_chromium_chromeos_compile_dbg_ng on master.tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  mac_chromium_rel_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[erikchen, 2016-07-12 22:13:47]

The CQ bit was checked by erikchen@chromium.org

[commit-bot: I haz the power, 2016-07-12 22:15:29]

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, 2016-07-13 00:13:07]

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

[commit-bot: I haz the power, 2016-07-13 00:13:08]

Try jobs failed on following builders:
  linux_chromium_asan_rel_ng on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  linux_chromium_chromeos_rel_ng on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[erikchen, 2016-07-13 00:14:35]

The CQ bit was checked by erikchen@chromium.org

[commit-bot: I haz the power, 2016-07-13 00:16:39]

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, 2016-07-13 03:15:27]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-07-13 03:18:43]

Description was changed from

==========
Fix preserve backbuffer with native GMBs.

The implementation of BackTexture::Copy was using glCopyTexImage2D, which
reallocates storage for the BackTexture. This doesn't work with native GMBs,
since they don't use traditional GL storage mechanisms. Switching to
glCopyTexSubImage2D fixes the problem, and is more efficient since storage has
already been allocated.

BUG=627332
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

==========
Fix preserve backbuffer with native GMBs.

The implementation of BackTexture::Copy was using glCopyTexImage2D, which
reallocates storage for the BackTexture. This doesn't work with native GMBs,
since they don't use traditional GL storage mechanisms. Switching to
glCopyTexSubImage2D fixes the problem, and is more efficient since storage has
already been allocated.

BUG=627332
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/2fc766777b27679b88b84561068ef189d550294a
Cr-Commit-Position: refs/heads/master@{#404945}
==========

[commit-bot: I haz the power, 2016-07-13 03:18:43]

Patchset 1 (id:??) landed as
https://crrev.com/2fc766777b27679b88b84561068ef189d550294a
Cr-Commit-Position: refs/heads/master@{#404945}