Make all GrXPFactory instances statics.

Change-Id: I423b821d96d483db8c43a6d5530adbc19cd68912
Reviewed-on: https://skia-review.googlesource.com/6693
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
2 files changed