Add basic SVD support to SkMatrix. Allows you to pull out the x- and y-scale factors, sandwiched by…

src/core/SkMatrixUtils.h

Index: src/core/SkMatrixUtils.h
diff --git a/src/core/SkMatrixUtils.h b/src/core/SkMatrixUtils.h
index 2074267b7df471b2ae02b7d86b1752a3ebf3f223..ee952b6f58296cc190756b947003e2c6200db4b0 100644
--- a/src/core/SkMatrixUtils.h
+++ b/src/core/SkMatrixUtils.h
@@ -40,4 +40,15 @@ static inline bool SkTreatAsSpriteFilter(const SkMatrix& matrix,
     return SkTreatAsSprite(matrix, width, height, kSkSubPixelBitsForBilerp);
 }
 
+/** Decomposes the upper-left 2x2 of the matrix into a rotation, followed by a non-uniform scale, 
+    followed by another rotation. Returns true if successful.
+    If the scale factors are uniform, then rotation1 will be 0.
+    If there is a reflection, yScale will be negative.
+    Returns false if the matrix is degenerate.
+    */
+bool SkDecomposeUpper2x2(const SkMatrix& matrix,
+                         SkScalar* rotation0, 
+                         SkScalar* xScale, SkScalar* yScale, 
+                         SkScalar* rotation1);
+
 #endif