Remove SkEncodedInfo kUnknown_Color and kUnknown_Alpha from public API

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 194 matching lines @@
         jpeg_save_markers(decoderMgr->dinfo(), kICCMarker, 0xFFFF);
     }
 
     // Read the jpeg header
     if (JPEG_HEADER_OK != jpeg_read_header(decoderMgr->dinfo(), true)) {
         return decoderMgr->returnFalse("read_header");
     }
 
     if (codecOut) {
         // Get the encoded color type
-        SkEncodedInfo::Color color = decoderMgr->getEncodedColor();
-        if (SkEncodedInfo::kUnknown_Color == color) {
+        SkEncodedInfo::Color color;
+        if (!decoderMgr->getEncodedColor(&color)) {
             return false;
         }
 
         // Create image info object and the codec
         SkEncodedInfo info = SkEncodedInfo::Make(color, SkEncodedInfo::kOpaque_Alpha, 8);
 
         Origin orientation = get_exif_orientation(decoderMgr->dinfo());
         sk_sp<SkColorSpace> colorSpace = get_icc_profile(decoderMgr->dinfo());
 
         const int width = decoderMgr->dinfo()->image_width;
@@ skipping 660 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;
 }