[Android] Support ALPHA_8 UI resources

[Android] Support ALPHA_8 UI resources

The new ResourceManager assumes the generated resource is of type
RGBA8. Add additional type support for A8, the format used by the
overscroll effect on Android L.

BUG=426939
Committed: https://crrev.com/c72103b1745f11339663ed926979a0ac3cc8c08e
Cr-Commit-Position: refs/heads/master@{#308013}

[jdduke (slow), 2014-12-11 23:11:23]

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

[jdduke (slow), 2014-12-11 23:11:23]

OK, let's give this a try =/

[David Trainor- moved to gerrit, 2014-12-11 23:13:12]

lgtm

[jdduke (slow), 2014-12-11 23:20:15]

The CQ bit was checked by jdduke@chromium.org

[commit-bot: I haz the power, 2014-12-11 23:20:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/798783002/1

[commit-bot: I haz the power, 2014-12-12 00:58:25]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-12-12 00:59:20]

Patchset 1 (id:??) landed as
https://crrev.com/c72103b1745f11339663ed926979a0ac3cc8c08e
Cr-Commit-Position: refs/heads/master@{#308013}