Fix a bug in compressed texture code path.

Fix a bug in compressed texture code path.

If we specify a texture using texStorage, the texture is uninitialized,
so if we call compressedTexSubImage, we need to consider the situation.

BUG=663960
TEST=webgl2_conformance (in https://github.com/KhronosGroup/WebGL/pull/2142)
R=piman@chromium.org,kbr@chromium.org
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

Committed: https://crrev.com/5219f45e8e6755153240985d4adeae6d27d69db7
Cr-Commit-Position: refs/heads/master@{#431642}

[Zhenyao Mo, 2016-11-11 19:31:15]

Description was changed from

==========
Fix a bug in compressed texture code path.

If we specify a texture using texStorage, the texture is uninitialized,
so if we call compressedTexSubImage, we need to consider the situation.

BUG=663960
TEST=webgl2_conformance (in https://github.com/KhronosGroup/WebGL/pull/2142)
R=piman@chromium.org,kbr@chromium.org
==========

to

==========
Fix a bug in compressed texture code path.

If we specify a texture using texStorage, the texture is uninitialized,
so if we call compressedTexSubImage, we need to consider the situation.

BUG=663960
TEST=webgl2_conformance (in https://github.com/KhronosGroup/WebGL/pull/2142)
R=piman@chromium.org,kbr@chromium.org
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
==========

[Zhenyao Mo, 2016-11-11 19:31:57]

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

[Zhenyao Mo, 2016-11-11 19:32:25]

PTAL.

Without this CL, https://github.com/KhronosGroup/WebGL/pull/2142 tests fail.

With this CL, the tests pass.

[commit-bot: I haz the power, 2016-11-11 19:32:27]

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, 2016-11-11 20:30:30]

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

[commit-bot: I haz the power, 2016-11-11 20:30:31]

Dry run: This issue passed the CQ dry run.

[Ken Russell (switch to Gerrit), 2016-11-11 20:58:01]

LGTM

Thanks for upgrading the conformance tests and sorry I missed testing this code
path in the first place.

(Antoine, the test I added first rendered from the texture allocated via
TexStorage2D, which cleared the level. Mo also added tests which allocated and
immediately populated it with CompressedTexStorage2D, which used to not work and
which regressed during the recent refactoring.)

I'm CQ'ing this now.

[Ken Russell (switch to Gerrit), 2016-11-11 20:58:04]

The CQ bit was checked by kbr@chromium.org

[commit-bot: I haz the power, 2016-11-11 20:58:41]

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, 2016-11-11 21:03:47]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-11-11 21:09:44]

Description was changed from

==========
Fix a bug in compressed texture code path.

If we specify a texture using texStorage, the texture is uninitialized,
so if we call compressedTexSubImage, we need to consider the situation.

BUG=663960
TEST=webgl2_conformance (in https://github.com/KhronosGroup/WebGL/pull/2142)
R=piman@chromium.org,kbr@chromium.org
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
==========

to

==========
Fix a bug in compressed texture code path.

If we specify a texture using texStorage, the texture is uninitialized,
so if we call compressedTexSubImage, we need to consider the situation.

BUG=663960
TEST=webgl2_conformance (in https://github.com/KhronosGroup/WebGL/pull/2142)
R=piman@chromium.org,kbr@chromium.org
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

Committed: https://crrev.com/5219f45e8e6755153240985d4adeae6d27d69db7
Cr-Commit-Position: refs/heads/master@{#431642}
==========

[commit-bot: I haz the power, 2016-11-11 21:09:45]

Patchset 1 (id:??) landed as
https://crrev.com/5219f45e8e6755153240985d4adeae6d27d69db7
Cr-Commit-Position: refs/heads/master@{#431642}