Initial change to move 2D kernel to its own file

include/effects/SkMatrixConvolutionImageFilter.h

Index: include/effects/SkMatrixConvolutionImageFilter.h
diff --git a/include/effects/SkMatrixConvolutionImageFilter.h b/include/effects/SkMatrixConvolutionImageFilter.h
index 6d4c8260388611dd5606873652f50705587f9895..0cb848b6319669050fe879df2f5fb02f865fddf7 100644
--- a/include/effects/SkMatrixConvolutionImageFilter.h
+++ b/include/effects/SkMatrixConvolutionImageFilter.h
@@ -23,9 +23,10 @@ class SK_API SkMatrixConvolutionImageFilter : public SkImageFilter {
 public:
     /*! \enum TileMode */
     enum TileMode {
-      kClamp_TileMode,         /*!< Clamp to the image's edge pixels. */
+      kClamp_TileMode = 0,         /*!< Clamp to the image's edge pixels. */
       kRepeat_TileMode,        /*!< Wrap around to the image's opposite edge. */
       kClampToBlack_TileMode,  /*!< Fill with transparent black. */
+      kMax_TileMode = kClampToBlack_TileMode
     };
 
     virtual ~SkMatrixConvolutionImageFilter();