replace setConfig+allocPixels with single call

tests/EmptyPathTest.cpp

Index: tests/EmptyPathTest.cpp
diff --git a/tests/EmptyPathTest.cpp b/tests/EmptyPathTest.cpp
index 09a1f5279c639fa6d363798ee9a1153540e851d3..c4f011a0dc65ae85b7c5421223d70ba8f2a909b6 100644
--- a/tests/EmptyPathTest.cpp
+++ b/tests/EmptyPathTest.cpp
@@ -14,9 +14,8 @@
 static void drawAndTest(skiatest::Reporter* reporter, const SkPath& path,
                         const SkPaint& paint, bool shouldDraw) {
     SkBitmap bm;
-    // explicitly specify a trim rowbytes, so we have no padding on each row
-    bm.setConfig(SkBitmap::kARGB_8888_Config, DIMENSION, DIMENSION, DIMENSION*4);
-    bm.allocPixels();
+    bm.allocN32Pixels(DIMENSION, DIMENSION);
+    SkASSERT(DIMENSION*4 == bm.rowBytes()); // ensure no padding on each row
     bm.eraseColor(SK_ColorTRANSPARENT);
 
     SkCanvas canvas(bm);