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.cpp b/libs/hwui/StatefulBaseRenderer.cpp
index 90039e9..fae25a6 100644
--- a/libs/hwui/StatefulBaseRenderer.cpp
+++ b/libs/hwui/StatefulBaseRenderer.cpp
@@ -121,20 +121,16 @@
     mSnapshot->transform->skew(sx, sy);
 }
 
-void StatefulBaseRenderer::setMatrix(const SkMatrix* matrix) {
-    if (matrix) {
-        mSnapshot->transform->load(*matrix);
-    } else {
-        mSnapshot->transform->loadIdentity();
-    }
+void StatefulBaseRenderer::setMatrix(const SkMatrix& matrix) {
+    mSnapshot->transform->load(matrix);
 }
 
 void StatefulBaseRenderer::setMatrix(const Matrix4& matrix) {
     mSnapshot->transform->load(matrix);
 }
 
-void StatefulBaseRenderer::concatMatrix(const SkMatrix* matrix) {
-    mat4 transform(*matrix);
+void StatefulBaseRenderer::concatMatrix(const SkMatrix& matrix) {
+    mat4 transform(matrix);
     mSnapshot->transform->multiply(transform);
 }