change more effects to only expose factories

src/effects/SkColorFilters.cpp

Index: src/effects/SkColorFilters.cpp
diff --git a/src/effects/SkColorFilters.cpp b/src/effects/SkColorFilters.cpp
index 1e34b1e5c356e24fc68bc33769246763885b42ea..4515c0d3fefa52b398f4d312e30008184cb6b7f9 100644
--- a/src/effects/SkColorFilters.cpp
+++ b/src/effects/SkColorFilters.cpp
@@ -166,7 +166,7 @@ SkColorFilter* SkColorFilter::CreateModeFilter(SkColor color, SkXfermode::Mode m
         case SkXfermode::kSrcOver_Mode:
             return new SrcOver_SkModeColorFilter(color);
         default:
-            return new SkModeColorFilter(color, mode);
+            return SkModeColorFilter::Create(color, mode);
     }
 }