Avoid unncessary EGLImageTargetTexture calls

Avoid unncessary EGLImageTargetTexture calls

EGLImageTargetTexture is expensive on some drivers, and can be skipped
if a texture is already bound to the EGLImage.

BUG=492315
Committed: https://crrev.com/043650c4a2dcb8f2be4a42781c090bb18d5d77f6
Cr-Commit-Position: refs/heads/master@{#332100}

[boliu, 2015-05-30 00:18:50]

boliu@chromium.org changed reviewers:
+ sievers@chromium.org

[boliu, 2015-05-30 00:18:50]

something like this?

[no sievers, 2015-05-30 00:42:48]

lgtm

[boliu, 2015-05-30 00:43:11]

The CQ bit was checked by boliu@chromium.org

[commit-bot: I haz the power, 2015-05-30 00:43:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1159293002/1

[commit-bot: I haz the power, 2015-05-30 02:08:25]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-30 02:09:31]

Patchset 1 (id:??) landed as
https://crrev.com/043650c4a2dcb8f2be4a42781c090bb18d5d77f6
Cr-Commit-Position: refs/heads/master@{#332100}