SkImageGeneratorCG.h to only expose factory method.

Instead of requiring the implementation details of the SkImageGenerator
which backs the CG image generator to be present in the header, move the
class into the implementation and only expose the factory method.

Change-Id: I728276ffcfb6bb4e7302280459a79210e8d67475
Reviewed-on: https://skia-review.googlesource.com/155611
Commit-Queue: Ben Wagner <bungeman@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Hal Canary <halcanary@google.com>
2 files changed