Fix colorType/alphaType checks in SkCodec

src/codec/SkJpegCodec.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 "SkCodec.h"
 #include "SkMSAN.h"
 #include "SkJpegCodec.h"
@@ skipping 336 matching lines @@
             case kRGB_565_SkColorType:
                 srcConfig = SkSwizzler::kNoOp16;
                 break;
             default:
                 // This function should only be called if the colorType is supported by jpeg
                 SkASSERT(false);
         }
     }
 
     fSwizzler.reset(SkSwizzler::CreateSwizzler(srcConfig, nullptr, dstInfo, options));
+    SkASSERT(fSwizzler);
     fStorage.reset(get_row_bytes(fDecoderMgr->dinfo()));
     fSrcRow = fStorage.get();
 }
 
 SkSampler* SkJpegCodec::getSampler(bool createIfNecessary) {
     if (!createIfNecessary || fSwizzler) {
         SkASSERT(!fSwizzler || (fSrcRow && fStorage.get() == fSrcRow));
         return fSwizzler;
     }
 
@@ skipping 279 matching lines @@
 
         JDIMENSION linesRead = jpeg_read_raw_data(dinfo, yuv, numRowsPerBlock);
         if (linesRead < remainingRows) {
             // FIXME: Handle incomplete YUV decodes without signalling an error.
             return kInvalidInput;
         }
     }
 
     return kSuccess;
 }