change all factories to return their base-class

include/effects/SkEmbossMaskFilter.h

 /*
  * Copyright 2006 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 SkEmbossMaskFilter_DEFINED
 #define SkEmbossMaskFilter_DEFINED
 
 #include "SkMaskFilter.h"
 
 /** \class SkEmbossMaskFilter
 
     This mask filter creates a 3D emboss look, by specifying a light and blur amount.
 */
 class SK_API SkEmbossMaskFilter : public SkMaskFilter {
 public:
     struct Light {
         SkScalar    fDirection[3];  // x,y,z
         uint16_t    fPad;
         uint8_t     fAmbient;
         uint8_t     fSpecular;      // exponent, 4.4 right now
     };
 
-    static SkEmbossMaskFilter* Create(SkScalar blurSigma, const Light& light);
+    static SkMaskFilter* Create(SkScalar blurSigma, const Light& light);
 
     // overrides from SkMaskFilter
     //  This method is not exported to java.
     SkMask::Format getFormat() const override;
     //  This method is not exported to java.
     bool filterMask(SkMask* dst, const SkMask& src, const SkMatrix&,
                     SkIPoint* margin) const override;
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkEmbossMaskFilter)
 
 protected:
     SkEmbossMaskFilter(SkScalar blurSigma, const Light& light);
     void flatten(SkWriteBuffer&) const override;
 
 private:
     Light       fLight;
     SkScalar    fBlurSigma;
 
     typedef SkMaskFilter INHERITED;
 };
 
 #endif