factories should return baseclass, allowing the impl to specialize

include/effects/SkPictureImageFilter.h

 /*
  * Copyright 2013 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 SkPictureImageFilter_DEFINED
 #define SkPictureImageFilter_DEFINED
 
 #include "SkImageFilter.h"
 #include "SkPicture.h"
 
 class SK_API SkPictureImageFilter : public SkImageFilter {
 public:
     /**
      *  Refs the passed-in picture.
      */
-    static SkPictureImageFilter* Create(const SkPicture* picture) {
+    static SkImageFilter* Create(const SkPicture* picture) {
         return new SkPictureImageFilter(picture);
     }
 
     /**
      *  Refs the passed-in picture. cropRect can be used to crop or expand the destination rect when
      *  the picture is drawn. (No scaling is implied by the dest rect; only the CTM is applied.)
      */
-    static SkPictureImageFilter* Create(const SkPicture* picture, const SkRect& cropRect) {
+    static SkImageFilter* Create(const SkPicture* picture, const SkRect& cropRect) {
         return new SkPictureImageFilter(picture, cropRect, kDeviceSpace_PictureResolution,
                                         kLow_SkFilterQuality);
     }
 
     /**
      *  Refs the passed-in picture. The picture is rasterized at a resolution that matches the
      *  local coordinate space. If the picture needs to be resampled for drawing it into the
      *  destination canvas, bilinear filtering will be used. cropRect can be used to crop or
      *  expand the destination rect when the picture is drawn. (No scaling is implied by the
      *  dest rect; only the CTM is applied.)
      */
-    static SkPictureImageFilter* CreateForLocalSpace(const SkPicture* picture,
+    static SkImageFilter* CreateForLocalSpace(const SkPicture* picture,
                                                      const SkRect& cropRect,
                                                      SkFilterQuality filterQuality) {
         return new SkPictureImageFilter(picture, cropRect, kLocalSpace_PictureResolution,
                                         filterQuality);
     }
+
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkPictureImageFilter)
 
 protected:
     enum PictureResolution {
         kDeviceSpace_PictureResolution,
         kLocalSpace_PictureResolution
     };
 
-    explicit SkPictureImageFilter(const SkPicture* picture);
-    SkPictureImageFilter(const SkPicture* picture, const SkRect& cropRect,
-                         PictureResolution, SkFilterQuality);
     virtual ~SkPictureImageFilter();
+
     /*  Constructs an SkPictureImageFilter object from an SkReadBuffer.
      *  Note: If the SkPictureImageFilter object construction requires bitmap
      *  decoding, the decoder must be set on the SkReadBuffer parameter by calling
      *  SkReadBuffer::setBitmapDecoder() before calling this constructor.
      *  @param SkReadBuffer Serialized picture data.
      */
     void flatten(SkWriteBuffer&) const override;
-    virtual bool onFilterImage(Proxy*, const SkBitmap& src, const Context&,
-                               SkBitmap* result, SkIPoint* offset) const override;
+    bool onFilterImage(Proxy*, const SkBitmap& src, const Context&, SkBitmap* result,
+                       SkIPoint* offset) const override;
 
 private:
-
+    explicit SkPictureImageFilter(const SkPicture* picture);
+    SkPictureImageFilter(const SkPicture* picture, const SkRect& cropRect,
+                         PictureResolution, SkFilterQuality);
 
     void drawPictureAtDeviceResolution(SkBaseDevice*, const SkIRect& deviceBounds,
                                        const Context&) const;
     void drawPictureAtLocalResolution(Proxy*, SkBaseDevice*, const SkIRect& deviceBounds,
                                       const Context&) const;
 
     const SkPicture*      fPicture;
     SkRect                fCropRect;
     PictureResolution     fPictureResolution;
     SkFilterQuality       fFilterQuality;
+
     typedef SkImageFilter INHERITED;
 };
 
 #endif