Revert of Fix colorType/alphaType checks in SkCodec

src/codec/SkGifCodec.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
 #include "SkColorTable.h"
@@ skipping 418 matching lines @@
         int* inputColorCount, const Options& opts) {
     // Check for valid input parameters
     if (!conversion_possible(dstInfo, this->getInfo())) {
         return gif_error("Cannot convert input type to output type.\n",
                 kInvalidConversion);
     }
 
     // Initialize color table and copy to the client if necessary
     this->initializeColorTable(dstInfo, inputColorPtr, inputColorCount);
 
-    this->initializeSwizzler(dstInfo, opts);
-    return kSuccess;
+    return this->initializeSwizzler(dstInfo, opts);
 }
 
-void SkGifCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Options& opts) {
+SkCodec::Result 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,
             frameRect));
-    SkASSERT(fSwizzler);
+
+    if (nullptr != fSwizzler.get()) {
+        return kSuccess;
+    }
+    return kUnimplemented;
 }
 
 bool SkGifCodec::readRow() {
     return GIF_ERROR != DGifGetLine(fGif, fSrcBuffer.get(), fFrameRect.width());
 }
 
 /*
  * Initiates the gif decode
  */
 SkCodec::Result SkGifCodec::onGetPixels(const SkImageInfo& dstInfo,
@@ skipping 117 matching lines @@
 int SkGifCodec::onOutputScanline(int inputScanline) const {
     if (fGif->Image.Interlace) {
         if (inputScanline < fFrameRect.top() || inputScanline >= fFrameRect.bottom()) {
             return inputScanline;
         }
         return get_output_row_interlaced(inputScanline - fFrameRect.top(), fFrameRect.height()) +
                 fFrameRect.top();
     }
     return inputScanline;
 }