hide virtual and rename to onMakeComposed

Bug: skia:
Change-Id: Ic18ee2af3273f81ebec9c9031162e808186c0acd
Reviewed-on: https://skia-review.googlesource.com/108300
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/tests/ColorFilterTest.cpp b/tests/ColorFilterTest.cpp
index c502a70..dc4a3a0 100644
--- a/tests/ColorFilterTest.cpp
+++ b/tests/ColorFilterTest.cpp
@@ -42,7 +42,7 @@
     auto parent(make_filter());
     for (int i = 2; i < way_too_many; ++i) {
         auto filter(make_filter());
-        parent = SkColorFilter::MakeComposeFilter(parent, filter);
+        parent = parent->makeComposed(filter);
         if (nullptr == parent) {
             REPORTER_ASSERT(reporter, i > 2); // we need to have succeeded at least once!
             return;