promote SkImage::AlphaType to SkAlphaType

BUG=
R=bsalomon@google.com

Review URL: https://codereview.chromium.org/24130009

git-svn-id: http://skia.googlecode.com/svn/trunk@11421 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tools/skhello.cpp b/tools/skhello.cpp
index bd31742..d30849b 100644
--- a/tools/skhello.cpp
+++ b/tools/skhello.cpp
@@ -30,10 +30,7 @@
 
 static bool do_surface(int w, int h, const char path[], const char text[],
                        const SkPaint& paint) {
-    SkImage::Info info = {
-        w, h, SkImage::kPMColor_ColorType, SkImage::kPremul_AlphaType
-    };
-    SkAutoTUnref<SkSurface> surface(SkSurface::NewRaster(info));
+    SkAutoTUnref<SkSurface> surface(SkSurface::NewRasterPMColor(w, h));
     doDraw(surface->getCanvas(), paint, text);
 
     SkAutoTUnref<SkImage> image(surface->newImageSnapshot());