move patheffect virtuals to protected and rename

- change filterPath to safely handle if src and dst are aliases

Bug: skia:8254
Change-Id: I125d19404ca0a610f73271abb5c5455d1d50f9ed
Reviewed-on: https://skia-review.googlesource.com/147466
Commit-Queue: Mike Reed <reed@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Auto-Submit: Mike Reed <reed@google.com>
diff --git a/src/gpu/GrTestUtils.h b/src/gpu/GrTestUtils.h
index 64c7662..ffc48aa 100644
--- a/src/gpu/GrTestUtils.h
+++ b/src/gpu/GrTestUtils.h
@@ -72,10 +72,12 @@
         return sk_sp<SkPathEffect>(new TestDashPathEffect(intervals, count, phase));
     }
 
-    bool filterPath(SkPath* dst, const SkPath&, SkStrokeRec* , const SkRect*) const override;
-    DashType asADash(DashInfo* info) const override;
     Factory getFactory() const override { return nullptr; }
 
+protected:
+    bool onFilterPath(SkPath* dst, const SkPath&, SkStrokeRec* , const SkRect*) const override;
+    DashType onAsADash(DashInfo* info) const override;
+
 private:
     TestDashPathEffect(const SkScalar* intervals, int count, SkScalar phase);