IWYU for some test files starting with 'C'.

Change-Id: I9a9596f7a941cdd8f01e055965c70a4b24438499
Reviewed-on: https://skia-review.googlesource.com/113746
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
16 files changed