Disable unused attributes when using copy shader

Disable unused attributes when using copy shader

BUG=chromium:496540
Committed: https://skia.googlesource.com/skia/+/d624634aff330485dc56fc09773cc6d4ec092c4d

[bsalomon, 2015-06-04 16:51:55]

bsalomon@google.com changed reviewers:
+ joshualitt@google.com

[bsalomon, 2015-06-04 16:51:59]

The CQ bit was checked by bsalomon@google.com

[commit-bot: I haz the power, 2015-06-04 16:52:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1157943007/1

[commit-bot: I haz the power, 2015-06-04 16:52:18]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2015-06-04 22:52 UTC

[joshualitt, 2015-06-04 16:59:43]

LGTM, probably not worth only doing this if we're in chromium.

[commit-bot: I haz the power, 2015-06-04 18:52:30]

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

[commit-bot: I haz the power, 2015-06-04 18:52:31]

Try jobs failed on following builders:
  Build-Mac10.8-Clang-x86_64-Release-Trybot on client.skia.compile
(JOB_TIMED_OUT, no build URL)

[bsalomon, 2015-06-04 19:17:49]

The CQ bit was checked by bsalomon@google.com

[commit-bot: I haz the power, 2015-06-04 19:18:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1157943007/1

[commit-bot: I haz the power, 2015-06-04 20:57:06]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/d624634aff330485dc56fc09773cc6d4ec092c4d