Remove SkEncodedInfo kUnknown_Color and kUnknown_Alpha from public API

src/codec/SkJpegDecoderMgr.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 "SkJpegDecoderMgr.h"
 
 #include "SkJpegUtility.h"
@@ skipping 17 matching lines @@
 bool JpegDecoderMgr::returnFalse(const char caller[]) {
     print_message((j_common_ptr) &fDInfo, caller);
     return false;
 }
 
 SkCodec::Result JpegDecoderMgr::returnFailure(const char caller[], SkCodec::Result result) {
     print_message((j_common_ptr) &fDInfo, caller);
     return result;
 }
 
-SkEncodedInfo::Color JpegDecoderMgr::getEncodedColor() {
+bool JpegDecoderMgr::getEncodedColor(SkEncodedInfo::Color* outColor) {
     switch (fDInfo.jpeg_color_space) {
         case JCS_GRAYSCALE:
-            return SkEncodedInfo::kGray_Color;
+            *outColor = SkEncodedInfo::kGray_Color;
+            return true;
         case JCS_YCbCr:
-            return SkEncodedInfo::kYUV_Color;
+            *outColor = SkEncodedInfo::kYUV_Color;
+            return true;
         case JCS_RGB:
-            return SkEncodedInfo::kRGB_Color;
+            *outColor = SkEncodedInfo::kRGB_Color;
+            return true;
         case JCS_YCCK:
-            return SkEncodedInfo::kYCCK_Color;
+            *outColor = SkEncodedInfo::kYCCK_Color;
+            return true;
         case JCS_CMYK:
-            return SkEncodedInfo::kInvertedCMYK_Color;
+            *outColor = SkEncodedInfo::kInvertedCMYK_Color;
+            return true;
         default:
-            return SkEncodedInfo::kUnknown_Color;
+            return false;
     }
 }
 
 JpegDecoderMgr::JpegDecoderMgr(SkStream* stream)
     : fSrcMgr(stream)
     , fInit(false)
 {
     // Error manager must be set before any calls to libjeg in order to handle failures
     fDInfo.err = jpeg_std_error(&fErrorMgr);
     fErrorMgr.error_exit = skjpeg_err_exit;
@@ skipping 12 matching lines @@
     }
 }
 
 jmp_buf& JpegDecoderMgr::getJmpBuf() {
     return fErrorMgr.fJmpBuf;
 }
 
 jpeg_decompress_struct* JpegDecoderMgr::dinfo() {
     return &fDInfo;
 }