Revert of SkImage_Codec is Lazy (https://codereview.chromium.org/460823002/)

Reason for revert:
breaks chromium - no SkDecodingImageGenerator::Create

Original issue's description:
> SkImage_Codec is Lazy
>
> Committed: https://skia.googlesource.com/skia/+/e36f499110da8c2e2aa05227bee6deb967309ead

R=reed@google.com
TBR=reed@google.com
NOTREECHECKS=true
NOTRY=true

Author: halcanary@google.com

Review URL: https://codereview.chromium.org/461043002
4 files changed