Try out SkMatrix::Concat.

tests/MatrixTest.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkMath.h"
 #include "SkMatrix.h"
 #include "SkMatrixUtils.h"
@@ skipping 767 matching lines @@
     mat.set(SkMatrix::kMSkewX, SK_ScalarNaN);
     mat2.set(SkMatrix::kMSkewX, SK_ScalarNaN);
     REPORTER_ASSERT(reporter, !are_equal(reporter, mat, mat2));
 
     test_matrix_min_max_stretch(reporter);
     test_matrix_is_similarity(reporter);
     test_matrix_recttorect(reporter);
     test_matrix_decomposition(reporter);
     test_matrix_homogeneous(reporter);
 }
+
+DEF_TEST(Matrix_Concat, r) {
+    SkMatrix a;
+    a.setTranslate(10, 20);
+
+    SkMatrix b;
+    b.setScale(3, 5);
+
+    SkMatrix expected;
+    expected.setConcat(a,b);
+
+    REPORTER_ASSERT(r, expected == SkMatrix::Concat(a, b));
+}