gpu, cmaa: copy RGBA8 texture via glCopyTexSubImage2D() instead of imageStore().

gpu, cmaa: copy RGBA8 texture via glCopyTexSubImage2D() instead of imageStore().

CMAA uses imageStore() to copy RGBA8 to RGBA8 texture. At the moment, we
expect the FBO is not updated. However, some drivers (e.g. Intel Mesa) fill
random color on the FBO in the case. It causes ugly artifact in the later CMAA
phase.
This CL copies RGBA8 texture via glCopyTexSubImage2D(), instead of custom shader and
glDrawArrays. It fixes the bug as well as speeds up copy.

BUG=642290
TEST=chromeos camera app on Samus
https://chrome.google.com/webstore/detail/camera/hfhhnacclhffhdffklopdkcgdhifgngh
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2298613010
Cr-Commit-Position: refs/heads/master@{#416538}
(cherry picked from commit b2d7e66345c253f353d1d3c555964f6e95e26b9c)

Committed: https://chromium.googlesource.com/chromium/src/+/41f75bc0f1ac9e8956007c1c7d95180e7efaf225

[robert.bradford, 2016-09-12 16:19:42]

Description was changed from

==========
gpu, cmaa: copy RGBA8 texture via glCopyTexSubImage2D() instead of imageStore().

CMAA uses imageStore() to copy RGBA8 to RGBA8 texture. At the moment, we
expect the FBO is not updated. However, some drivers (e.g. Intel Mesa) fill
random color on the FBO in the case. It causes ugly artifact in the later CMAA
phase.
This CL copies RGBA8 texture via glCopyTexSubImage2D(), instead of custom shader
and
glDrawArrays. It fixes the bug as well as speeds up copy.

BUG=642290
TEST=chromeos camera app on Samus
https://chrome.google.com/webstore/detail/camera/hfhhnacclhffhdffklopdkcgdhif...
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2298613010
Cr-Commit-Position: refs/heads/master@{#416538}
(cherry picked from commit b2d7e66345c253f353d1d3c555964f6e95e26b9c)
==========

to

==========
gpu, cmaa: copy RGBA8 texture via glCopyTexSubImage2D() instead of imageStore().

CMAA uses imageStore() to copy RGBA8 to RGBA8 texture. At the moment, we
expect the FBO is not updated. However, some drivers (e.g. Intel Mesa) fill
random color on the FBO in the case. It causes ugly artifact in the later CMAA
phase.
This CL copies RGBA8 texture via glCopyTexSubImage2D(), instead of custom shader
and
glDrawArrays. It fixes the bug as well as speeds up copy.

BUG=642290
TEST=chromeos camera app on Samus
https://chrome.google.com/webstore/detail/camera/hfhhnacclhffhdffklopdkcgdhif...
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2298613010
Cr-Commit-Position: refs/heads/master@{#416538}
(cherry picked from commit b2d7e66345c253f353d1d3c555964f6e95e26b9c)

Committed:
https://chromium.googlesource.com/chromium/src/+/41f75bc0f1ac9e8956007c1c7d95...
==========

[robert.bradford, 2016-09-12 16:19:44]

Committed patchset #1 (id:1) manually as
41f75bc0f1ac9e8956007c1c7d95180e7efaf225.