Support RGBA/BGRA swizzles using SkEncodedInfo

src/codec/SkPngCodec.h

Index: src/codec/SkPngCodec.h
diff --git a/src/codec/SkPngCodec.h b/src/codec/SkPngCodec.h
index 3f8a5d3d0cc74d63488d787c4602f63368f89f22..d69b28aae868737252832b7bf168e68e5e3c98b9 100644
--- a/src/codec/SkPngCodec.h
+++ b/src/codec/SkPngCodec.h
@@ -46,7 +46,6 @@ protected:
 
     png_structp png_ptr() { return fPng_ptr; }
     SkSwizzler* swizzler() { return fSwizzler; }
-    SkSwizzler::SrcConfig srcConfig() const { return fSrcConfig; }
     int numberPasses() const { return fNumberPasses; }
 
 private:
@@ -58,11 +57,10 @@ private:
     SkAutoTUnref<SkColorTable>      fColorTable;    // May be unpremul.
     SkAutoTDelete<SkSwizzler>       fSwizzler;
 
-    SkSwizzler::SrcConfig           fSrcConfig;
     const int                       fNumberPasses;
     int                             fBitDepth;
 
-    bool decodePalette(bool premultiply, int* ctableCount);
+    bool decodePalette(bool premultiply, SkColorType dstColorType, int* ctableCount);
     void destroyReadStruct();
 
     typedef SkCodec INHERITED;