Revert of change pixel-serializer to support reencoding existing data

Revert of change pixel-serializer to support reencoding existing data (patchset #5 id:80001 of https://codereview.chromium.org/1373683003/ )

Reason for revert:
Need to somehow get access to encoders in chrome -- link error on the roll since SkImageEncoder is not built as part of chrome.

Original issue's description:
> change pixel-serializer to support reencoding existing data
> 
> Trying to evolve this interface so it can
> - support rich set of backend-encoders (including ones like ETC1 that can cheaply convert to KXT
> - allow for encoding images as well as bitmaps (e.g. for picture serialization)
> - perhaps replace SkImageEncoder as an API (assuming we create a factory that returns a serializer given a format)
> 
> BUG=skia:
> 
> Committed: https://skia.googlesource.com/skia/+/13f48dc85aa68a60da66aaf39c93d527d11d1278

TBR=scroggo@google.com,msarett@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Committed: https://skia.googlesource.com/skia/+/c9e190ddac3d193e89e580ea3819a55c28f15e61

[reed1, 2015-09-28 16:58:23]

Created Revert of change pixel-serializer to support reencoding existing data

[commit-bot: I haz the power, 2015-09-28 16:58:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1371983003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1371983003/1

[commit-bot: I haz the power, 2015-09-28 16:58:44]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/c9e190ddac3d193e89e580ea3819a55c28f15e61