Separate SkArithmeticImageFilter from SkXfermodeImageFilter.

Change-Id: I145eed7276456b546ca5c66bc1a0f0f74a84f138
Reviewed-on: https://skia-review.googlesource.com/6728
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/gm/xfermodeimagefilter.cpp b/gm/xfermodeimagefilter.cpp
index 9190859..77c3502 100644
--- a/gm/xfermodeimagefilter.cpp
+++ b/gm/xfermodeimagefilter.cpp
@@ -7,6 +7,7 @@
 
 #include "gm.h"
 #include "sk_tool_utils.h"
+#include "SkArithmeticImageFilter.h"
 #include "SkImage.h"
 #include "SkImageSource.h"
 #include "SkOffsetImageFilter.h"
@@ -95,7 +96,7 @@
             }
         }
         // Test arithmetic mode as image filter
-        paint.setImageFilter(SkXfermodeImageFilter::MakeArithmetic(0, 1, 1, 0, true, background));
+        paint.setImageFilter(SkArithmeticImageFilter::Make(0, 1, 1, 0, true, background));
         DrawClippedBitmap(canvas, fBitmap, paint, x, y);
         x += fBitmap.width() + MARGIN;
         if (x + fBitmap.width() > WIDTH) {