Revert of Add SkEncodedInfo to report properties of encoded image data

src/codec/SkGifCodec.cpp

Index: src/codec/SkGifCodec.cpp
diff --git a/src/codec/SkGifCodec.cpp b/src/codec/SkGifCodec.cpp
index cdd9d088f129d2b80055bc5a8e24755ffd1c7f0f..2233c66c19f5ca81ac002f2f46bce377fc7e80d1 100644
--- a/src/codec/SkGifCodec.cpp
+++ b/src/codec/SkGifCodec.cpp
@@ -199,23 +199,25 @@
         }
         bool frameIsSubset = (size != frameRect.size());
 
-        // Determine the encoded alpha type.  The transIndex might be valid if it less
+        // Determine the recommended alpha type.  The transIndex might be valid if it less
         // than 256.  We are not certain that the index is valid until we process the color
         // table, since some gifs have color tables with less than 256 colors.  If
         // there might be a valid transparent index, we must indicate that the image has
         // alpha.
-        // In the case where we must support alpha, we indicate kBinary, since every
-        // pixel will either be fully opaque or fully transparent.
-        SkEncodedInfo::Alpha alpha = (transIndex < 256) ? SkEncodedInfo::kBinary_Alpha :
-                SkEncodedInfo::kOpaque_Alpha;
+        // In the case where we must support alpha, we have the option to set the
+        // suggested alpha type to kPremul or kUnpremul.  Both are valid since the alpha
+        // component will always be 0xFF or the entire 32-bit pixel will be set to zero.
+        // We prefer kPremul because we support kPremul, and it is more efficient to use
+        // kPremul directly even when kUnpremul is supported.
+        SkAlphaType alphaType = (transIndex < 256) ? kPremul_SkAlphaType : kOpaque_SkAlphaType;
 
         // Return the codec
-        // Use kPalette since Gifs are encoded with a color table.
-        // Use 8-bits per component, since this is the output we get from giflib.
-        // FIXME: Gifs can actually be encoded with 4-bits per pixel.  Can we support this?
-        SkEncodedInfo info = SkEncodedInfo::Make(SkEncodedInfo::kPalette_Color, alpha, 8);
-        *codecOut = new SkGifCodec(size.width(), size.height(), info, streamDeleter.release(),
-                gif.release(), transIndex, frameRect, frameIsSubset);
+        // kIndex is the most natural color type for gifs, so we set this as
+        // the default.
+        SkImageInfo imageInfo = SkImageInfo::Make(size.width(), size.height(), kIndex_8_SkColorType,
+                alphaType);
+        *codecOut = new SkGifCodec(imageInfo, streamDeleter.release(), gif.release(), transIndex,
+                frameRect, frameIsSubset);
     } else {
         SkASSERT(nullptr != gifOut);
         streamDeleter.release();
@@ -237,9 +239,9 @@
     return nullptr;
 }
 
-SkGifCodec::SkGifCodec(int width, int height, const SkEncodedInfo& info, SkStream* stream,
-        GifFileType* gif, uint32_t transIndex, const SkIRect& frameRect, bool frameIsSubset)
-    : INHERITED(width, height, info, stream)
+SkGifCodec::SkGifCodec(const SkImageInfo& srcInfo, SkStream* stream, GifFileType* gif,
+        uint32_t transIndex, const SkIRect& frameRect, bool frameIsSubset)
+    : INHERITED(srcInfo, stream)
     , fGif(gif)
     , fSrcBuffer(new uint8_t[this->getInfo().width()])
     , fFrameRect(frameRect)