SkBlurDrawLooper: Start by deleting flags

Android is the only user of this looper.  They never pass any flags.

BUG=skia:

Change-Id: I87b02ef7bc0ed94bca82637d60adddf34575a3e6
Reviewed-on: https://skia-review.googlesource.com/10057
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Mike Reed <reed@google.com>
6 files changed