replace setConfig+allocPixels with single call

BUG=skia:

Review URL: https://codereview.chromium.org/162643002

git-svn-id: http://skia.googlecode.com/svn/trunk@13426 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/SurfaceTest.cpp b/tests/SurfaceTest.cpp
index 8075913..aa457c7 100644
--- a/tests/SurfaceTest.cpp
+++ b/tests/SurfaceTest.cpp
@@ -178,8 +178,7 @@
     const size_t testPointCount = 3;
 
     SkBitmap testBitmap;
-    testBitmap.setConfig(SkBitmap::kARGB_8888_Config, 10, 10);
-    testBitmap.allocPixels();
+    testBitmap.allocN32Pixels(10, 10);
     testBitmap.eraseColor(0);
 
     SkRRect testRRect;