Use forward declare of SkEncodedImageFormat
Use forward declare of SkEncodedImageFormat

Client changes:
 - http://cl/484581917
 - http://cl/484583432
 - https://crrev.com/c/3991332
 - https://github.com/flutter/engine/pull/37201

Change-Id: If3ab1fa72c333cbf4696be76e75c46c5b9c41ee3
Bug: skia:13052
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/597559
Reviewed-by: Ben Wagner <53965154ffeecc4a10886eab9259e95965f2979a@google.com>
Owners-Override: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@google.com>

google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia