Clean up SkImageFilter constructors.

src/effects/SkXfermodeImageFilter.cpp

Index: src/effects/SkXfermodeImageFilter.cpp
diff --git a/src/effects/SkXfermodeImageFilter.cpp b/src/effects/SkXfermodeImageFilter.cpp
index acb8fd381b88cf9c3f89c3a7e045c5879206a869..bcfb78576e3fa647a2de241ad75c54b301ebb565 100644
--- a/src/effects/SkXfermodeImageFilter.cpp
+++ b/src/effects/SkXfermodeImageFilter.cpp
@@ -21,10 +21,9 @@
 ///////////////////////////////////////////////////////////////////////////////
 
 SkXfermodeImageFilter::SkXfermodeImageFilter(SkXfermode* mode,
-                                             SkImageFilter* background,
-                                             SkImageFilter* foreground,
+                                             SkImageFilter* inputs[2],
                                              const CropRect* cropRect)
-  : INHERITED(background, foreground, cropRect), fMode(mode) {
+  : INHERITED(2, inputs, cropRect), fMode(mode) {
     SkSafeRef(fMode);
 }