Clean up SkImageFilter constructors.

include/effects/SkDisplacementMapEffect.h

Index: include/effects/SkDisplacementMapEffect.h
diff --git a/include/effects/SkDisplacementMapEffect.h b/include/effects/SkDisplacementMapEffect.h
index 4d64aaeb41d3f19f437f6af88c6bde0c013e95ee..07f8ee9e85efe05c57e71d0b99c54a4c194706ea 100644
--- a/include/effects/SkDisplacementMapEffect.h
+++ b/include/effects/SkDisplacementMapEffect.h
@@ -28,8 +28,9 @@ public:
                                            SkScalar scale, SkImageFilter* displacement,
                                            SkImageFilter* color = NULL,
                                            const CropRect* cropRect = NULL) {
+        SkImageFilter* inputs[2] = { displacement, color };
         return SkNEW_ARGS(SkDisplacementMapEffect, (xChannelSelector, yChannelSelector, scale,
-                                                    displacement, color, cropRect));
+                                                    inputs, cropRect));
     }
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkDisplacementMapEffect)
@@ -53,9 +54,8 @@ public:
 protected:
     SkDisplacementMapEffect(ChannelSelectorType xChannelSelector,
                             ChannelSelectorType yChannelSelector,
-                            SkScalar scale, SkImageFilter* displacement,
-                            SkImageFilter* color = NULL,
-                            const CropRect* cropRect = NULL);
+                            SkScalar scale, SkImageFilter* inputs[2],
+                            const CropRect* cropRect);
     explicit SkDisplacementMapEffect(SkReadBuffer& buffer);
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;