exo: Avoid creating transparent texture quads.

exo: Avoid creating transparent texture quads.

The surface is fully transparent when alpha is 0 and we can then
avoid to create a texture quad completely. Failing to do so
currently results in unnecessary compositing.

BUG=640805
TEST=exo_unittests

Review-Url: https://codereview.chromium.org/2277833004
Cr-Commit-Position: refs/heads/master@{#414220}
(cherry picked from commit e2d54b85fbc32bd0d19e1741677a296e25fd47c7)

Committed: https://chromium.googlesource.com/chromium/src/+/8b50ca09664b21db2a2abb04d76199daf347b3bd

[reveman, 2016-08-30 21:03:45]

Description was changed from

==========
exo: Avoid creating transparent texture quads.

The surface is fully transparent when alpha is 0 and we can then
avoid to create a texture quad completely. Failing to do so
currently results in unnecessary compositing.

BUG=640805
TEST=exo_unittests

Review-Url: https://codereview.chromium.org/2277833004
Cr-Commit-Position: refs/heads/master@{#414220}
(cherry picked from commit e2d54b85fbc32bd0d19e1741677a296e25fd47c7)
==========

to

==========
exo: Avoid creating transparent texture quads.

The surface is fully transparent when alpha is 0 and we can then
avoid to create a texture quad completely. Failing to do so
currently results in unnecessary compositing.

BUG=640805
TEST=exo_unittests

Review-Url: https://codereview.chromium.org/2277833004
Cr-Commit-Position: refs/heads/master@{#414220}
(cherry picked from commit e2d54b85fbc32bd0d19e1741677a296e25fd47c7)

Committed:
https://chromium.googlesource.com/chromium/src/+/8b50ca09664b21db2a2abb04d761...
==========

[reveman, 2016-08-30 21:03:46]

Committed patchset #1 (id:1) manually as
8b50ca09664b21db2a2abb04d76199daf347b3bd.