Add an SkImageGeneratorCG

src/codec/SkCodecImageGenerator.cpp

Index: src/codec/SkCodecImageGenerator.cpp
diff --git a/src/codec/SkCodecImageGenerator.cpp b/src/codec/SkCodecImageGenerator.cpp
index e6e164ef6137ba358b2b769a928f5af98ade8bab..0d0380b52226d8a68001a6bfb12bb8291b0e8a27 100644
--- a/src/codec/SkCodecImageGenerator.cpp
+++ b/src/codec/SkCodecImageGenerator.cpp
@@ -16,16 +16,8 @@ SkImageGenerator* SkCodecImageGenerator::NewFromEncodedCodec(SkData* data) {
     return new SkCodecImageGenerator(codec, data);
 }
 
-static SkImageInfo make_premul(const SkImageInfo& info) {
-    if (kUnpremul_SkAlphaType == info.alphaType()) {
-        return info.makeAlphaType(kPremul_SkAlphaType);
-    }
-
-    return info;
-}
-
 SkCodecImageGenerator::SkCodecImageGenerator(SkCodec* codec, SkData* data)
-    : INHERITED(make_premul(codec->getInfo()))
+    : INHERITED(codec->getInfo())
     , fCodec(codec)
     , fData(SkRef(data))
     , fYWidth(0)