Clean up SkImageFilter constructors.

include/effects/SkLightingImageFilter.h

 /*
  * Copyright 2012 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkLightingImageFilter_DEFINED
 #define SkLightingImageFilter_DEFINED
 
@@ skipping 55 matching lines @@
         SkColor lightColor, SkScalar surfaceScale, SkScalar ks,
         SkScalar shininess, SkImageFilter* input = NULL, const CropRect* cropRect = NULL);
     ~SkLightingImageFilter();
 
     SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
 
 protected:
     SkLightingImageFilter(SkLight* light,
                           SkScalar surfaceScale,
                           SkImageFilter* input,
-                          const CropRect* cropRect = NULL);
+                          const CropRect* cropRect);
     explicit SkLightingImageFilter(SkReadBuffer& buffer);
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
     const SkLight* light() const { return fLight; }
     SkScalar surfaceScale() const { return fSurfaceScale; }
 
 private:
     typedef SkImageFilter INHERITED;
     SkLight* fLight;
     SkScalar fSurfaceScale;
 };
 
 #endif