Revert of default SkPixelSerializer (patchset #2 id:20001 of https://codereview.chromium.org/1507123002/ )

Reason for revert:
I was overconfident.

Original issue's description:
> default SkPixelSerializer
>
> Add SkImageEncoder::EncodeData(const SkPixmap&, ...) function.
>
> Add SkImageEncoder::CreatePixelSerializer() to return a
> PixelSerializer that calls into SkImageEncoder::EncodeData.
>
> SkImage::encode() make use of SkImageEncoder::CreatePixelSerializer.
>
> Committed: https://skia.googlesource.com/skia/+/b0bd1516bff3f5afcbfd615e805867531657811b
>
> Committed: https://skia.googlesource.com/skia/+/808ce2886d732b1055f89c8fb0f1b11b47fcb0ce

TBR=reed@google.com,scroggo@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1511183002
7 files changed