Add matrix constructing helpers to SkMatrix

bench/HairlinePathBench.cpp

Index: bench/HairlinePathBench.cpp
diff --git a/bench/HairlinePathBench.cpp b/bench/HairlinePathBench.cpp
index 5b77ff8b49cb32eb891ec597b8e423fbefbd93c4..67f54767244ea7df3c4e0c53b5e620f4b129c8fe 100644
--- a/bench/HairlinePathBench.cpp
+++ b/bench/HairlinePathBench.cpp
@@ -59,8 +59,7 @@ protected:
         SkPath path;
         this->makePath(&path);
         if (fFlags & kBig_Flag) {
-            SkMatrix m;
-            m.setScale(SkIntToScalar(3), SkIntToScalar(3));
+            const SkMatrix m = SkMatrix::MakeScale(SkIntToScalar(3), SkIntToScalar(3));
             path.transform(m);
         }