Support RGBA/BGRA swizzles using SkEncodedInfo

src/codec/SkGifCodec.cpp

Index: src/codec/SkGifCodec.cpp
diff --git a/src/codec/SkGifCodec.cpp b/src/codec/SkGifCodec.cpp
index 3304a5386c93db2e7641d9ad1e172c2ea2be49ef..15c134029c0288309b37eee894c89592330d40cf 100644
--- a/src/codec/SkGifCodec.cpp
+++ b/src/codec/SkGifCodec.cpp
@@ -410,8 +410,9 @@ void SkGifCodec::initializeColorTable(const SkImageInfo& dstInfo, SkPMColor* inp
         // giflib guarantees these properties
         SkASSERT(colorCount == (unsigned) (1 << (colorMap->BitsPerPixel)));
         SkASSERT(colorCount <= 256);
+        PackColorProc proc = choose_pack_color_proc(false, dstInfo.colorType());
         for (uint32_t i = 0; i < colorCount; i++) {
-            colorPtr[i] = SkPackARGB32(0xFF, colorMap->Colors[i].Red,
+            colorPtr[i] = proc(0xFF, colorMap->Colors[i].Red,
                     colorMap->Colors[i].Green, colorMap->Colors[i].Blue);
         }
     }
@@ -464,7 +465,7 @@ SkCodec::Result SkGifCodec::prepareToDecode(const SkImageInfo& dstInfo, SkPMColo
 void SkGifCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Options& opts) {
     const SkPMColor* colorPtr = get_color_ptr(fColorTable.get());
     const SkIRect* frameRect = fFrameIsSubset ? &fFrameRect : nullptr;
-    fSwizzler.reset(SkSwizzler::CreateSwizzler(SkSwizzler::kIndex, colorPtr, dstInfo, opts,
+    fSwizzler.reset(SkSwizzler::CreateSwizzler(this->getEncodedInfo(), colorPtr, dstInfo, opts,
             frameRect));
     SkASSERT(fSwizzler);
 }