Stop incorrectly caching brightness values

Stop incorrectly caching brightness values

NOTE: this change will incur an allocation on every update
if the brightness value is less than 1.0.

BUG=474612
Committed: https://crrev.com/63f37382e88ffe66d58cd9c19beaf182cd5caca0
Cr-Commit-Position: refs/heads/master@{#325226}

[aruslan, 2015-04-15 00:40:11]

aruslan@chromium.org changed reviewers:
+ dtrainor@chromium.org

[aruslan, 2015-04-15 00:40:11]

Let's talk about this. We have two unrelated drivers of the content_layer
filters.

[David Trainor- moved to gerrit, 2015-04-15 07:30:39]

lgtm

[aruslan, 2015-04-15 11:56:04]

The CQ bit was checked by aruslan@chromium.org

[commit-bot: I haz the power, 2015-04-15 11:56:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1083203002/20001

[commit-bot: I haz the power, 2015-04-15 11:59:29]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-15 12:00:24]

Patchset 2 (id:??) landed as
https://crrev.com/63f37382e88ffe66d58cd9c19beaf182cd5caca0
Cr-Commit-Position: refs/heads/master@{#325226}