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/tests/SurfaceTest.cpp b/tests/SurfaceTest.cpp
index 049f250..80822a1 100644
--- a/tests/SurfaceTest.cpp
+++ b/tests/SurfaceTest.cpp
@@ -28,7 +28,7 @@
         10,  // width
         10,  // height
         SkImage::kPMColor_ColorType,
-        SkImage::kPremul_AlphaType
+        kPremul_SkAlphaType
     };
 
     switch (surfaceType) {