Move headers with no dependencies.

C.f.  https://codereview.chromium.org/1261013003/

BUG=skia:4126

Will follow up with two more CLs if this works:
  - one moving SkRecords.h
  - one moving SkMiniRecorder.h

No public API changes.
TBR=reed@google.com

Committed: https://skia.googlesource.com/skia/+/117842223bd13325b6da26110d80e0590c1a742b

Review URL: https://codereview.chromium.org/1266593002
4 files changed