use SkColorType instead of SkBitmap::Config in samplecode

BUG=skia:
R=reed@google.com

Author: reed@chromium.org

Review URL: https://codereview.chromium.org/169063002

git-svn-id: http://skia.googlecode.com/svn/trunk@13473 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SampleVertices.cpp b/samplecode/SampleVertices.cpp
index 323c4b5..4c3a17e 100644
--- a/samplecode/SampleVertices.cpp
+++ b/samplecode/SampleVertices.cpp
@@ -28,10 +28,9 @@
 static SkShader* make_shader0(SkIPoint* size) {
     SkBitmap    bm;
     size->set(2, 2);
-    bm.setConfig(SkBitmap::kARGB_8888_Config, size->fX, size->fY);
     SkPMColor color0 = SkPreMultiplyARGB(0x80, 0x80, 0xff, 0x80);
     SkPMColor color1 = SkPreMultiplyARGB(0x40, 0xff, 0x00, 0xff);
-    bm.allocPixels();
+    bm.allocN32Pixels(size->fX, size->fY);
     bm.eraseColor(color0);
     bm.lockPixels();
     uint32_t* pixels = (uint32_t*) bm.getPixels();