hide Config in SkImageDecoder -- use SkColorType instead

gm/gm_expectations.cpp

Index: gm/gm_expectations.cpp
diff --git a/gm/gm_expectations.cpp b/gm/gm_expectations.cpp
index d2d629e8d3d6f61c0c72497d0415742ea710a5c1..f0ccb3e378b6bd28d58d4ea79a9f06f118241627 100644
--- a/gm/gm_expectations.cpp
+++ b/gm/gm_expectations.cpp
@@ -207,10 +207,8 @@ namespace skiagm {
         SkString path = SkOSPath::SkPathJoin(fRootDir.c_str(), testName);
         SkBitmap referenceBitmap;
         bool decodedReferenceBitmap =
-            SkImageDecoder::DecodeFile(path.c_str(), &referenceBitmap,
-                                       SkBitmap::kARGB_8888_Config,
-                                       SkImageDecoder::kDecodePixels_Mode,
-                                       NULL);
+            SkImageDecoder::DecodeFile(path.c_str(), &referenceBitmap, kN32_SkColorType,
+                                       SkImageDecoder::kDecodePixels_Mode, NULL);
         if (decodedReferenceBitmap) {
             return Expectations(referenceBitmap);
         } else {