Update HWUI matrix API

1. more closely mirror Skia API by using const ref instead of ptrs
2. store SkMatrix in the drawOp instead of the linear allocation heap

Change-Id: I4b9f6f76b9f7d19325e29303d27b793679fd4823
diff --git a/libs/hwui/StatefulBaseRenderer.h b/libs/hwui/StatefulBaseRenderer.h
index 057006b..f38c752 100644
--- a/libs/hwui/StatefulBaseRenderer.h
+++ b/libs/hwui/StatefulBaseRenderer.h
@@ -75,9 +75,9 @@
     virtual void scale(float sx, float sy);
     virtual void skew(float sx, float sy);
 
-    virtual void setMatrix(const SkMatrix* matrix);
+    virtual void setMatrix(const SkMatrix& matrix);
     void setMatrix(const Matrix4& matrix); // internal only convenience method
-    virtual void concatMatrix(const SkMatrix* matrix);
+    virtual void concatMatrix(const SkMatrix& matrix);
     void concatMatrix(const Matrix4& matrix); // internal only convenience method
 
     // Clip