Remove code to register Pepper effects plugin

Remove code to register Pepper effects plugin.

The effects functionality has been migrated to NaCl - the code to
manually register a Pepper plugin for Effects is no longer needed.

BUG=392002
TEST=trybots, unit_tests

Committed: https://crrev.com/a5ec7f353de81919132ebaff7c6381c00a9d7f3c
Cr-Commit-Position: refs/heads/master@{#325460}

[Josh Horwich, 2015-04-16 00:22:33]

jhorwich@chromium.org changed reviewers:
+ jam@chromium.org

[jam, 2015-04-16 04:08:51]

lgtm

[Josh Horwich, 2015-04-16 17:09:23]

The CQ bit was checked by jhorwich@chromium.org

[commit-bot: I haz the power, 2015-04-16 17:09:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1085393003/1

[commit-bot: I haz the power, 2015-04-16 17:16:08]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-16 17:18:01]

Patchset 1 (id:??) landed as
https://crrev.com/a5ec7f353de81919132ebaff7c6381c00a9d7f3c
Cr-Commit-Position: refs/heads/master@{#325460}