Fix uninitialized values in FuzzCanvas

BUG=skia:

Change-Id: I45cb8a2d0695ec9a065ea9dd216e5d0220ad5a98
Reviewed-on: https://skia-review.googlesource.com/9690
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
1 file changed