GM : Unused parameters cleanup

I removed unused parameters in the gms wherever it was trivial to do so. I'm
trying to get the easy ones out of the way before we get into more involved
discussions around this.
Review URL: https://codereview.appspot.com/7398056

git-svn-id: http://skia.googlecode.com/svn/trunk@7881 2bbb7eff-a529-9590-31e7-b0007b416f81
4 files changed