Alternate version of SkLocalMatrixImageFilter using an input.

include/core/SkImageFilter.h

Index: include/core/SkImageFilter.h
diff --git a/include/core/SkImageFilter.h b/include/core/SkImageFilter.h
index 0595010c6fba0321262feca28b887ce3bf272649..c913f8e31222e7389abb35fa397563116d67e4a1 100644
--- a/include/core/SkImageFilter.h
+++ b/include/core/SkImageFilter.h
@@ -230,6 +230,12 @@ public:
     bool canComputeFastBounds() const;
 
     /**
+     *  If this filter can be represented by another filter + a localMatrix, return that filter,
+     *  else return null.
+     */
+    virtual SkImageFilter* newWithLocalMatrix(const SkMatrix& localMatrix) const;
+
+    /**
      * Create an SkMatrixImageFilter, which transforms its input by the given matrix.
      */
     static SkImageFilter* CreateMatrixFilter(const SkMatrix& matrix,
@@ -387,9 +393,10 @@ protected:
 
 private:
     friend class SkGraphics;
-    static void PurgeCache();
+    friend class SkLocalMatrixImageFilter;
 
     bool usesSrcInput() const { return fUsesSrcInput; }
+    static void PurgeCache();
 
     typedef SkFlattenable INHERITED;
     int fInputCount;