Use SkJpegEncoder in gfx jpeg_codec

ui/gfx/codec/jpeg_codec.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_CODEC_JPEG_CODEC_H_
 #define UI_GFX_CODEC_JPEG_CODEC_H_
 
 #include <stddef.h>
 
 #include <memory>
 #include <vector>
 
+#include "third_party/skia/include/core/SkImageInfo.h"
 #include "ui/gfx/codec/codec_export.h"
 
 class SkBitmap;
 
 namespace gfx {
 
 // Interface for encoding/decoding JPEG data. This is a wrapper around libjpeg,
 // which has an inconvenient interface for callers. This is only used for UI
 // elements, WebKit has its own more complicated JPEG decoder which handles,
 // among other things, partially downloaded data.
 class CODEC_EXPORT JPEGCodec {
  public:
   enum ColorFormat {
-    // 3 bytes per pixel (packed), in RGB order regardless of endianness.
-    // This is the native JPEG format.
-    FORMAT_RGB,
-
     // 4 bytes per pixel, in RGBA order in mem regardless of endianness.
     FORMAT_RGBA,
 
     // 4 bytes per pixel, in BGRA order in mem regardless of endianness.
     // This is the default Windows DIB order.
     FORMAT_BGRA,
 
     // 4 bytes per pixel, it can be either RGBA or BGRA. It depends on the bit
     // order in kARGB_8888_Config skia bitmap.
     FORMAT_SkBitmap
   };
 
   enum LibraryVariant {
     SYSTEM_LIBJPEG = 0,
     LIBJPEG_TURBO,
     IJG_LIBJPEG,
   };
 
   // This method helps identify at run time which library chromium is using.
   static LibraryVariant JpegLibraryVariant();
 
   // Encodes the given raw 'input' data, with each pixel being represented as
-  // given in 'format'. The encoded JPEG data will be written into the supplied
-  // vector and true will be returned on success. On failure (false), the
-  // contents of the output buffer are undefined.
+  // given in 'colorType'. The encoded JPEG data will be written into the
+  // supplied vector and true will be returned on success. On failure (false),
+  // the contents of the output buffer are undefined.
   //
   // w, h: dimensions of the image
   // row_byte_width: the width in bytes of each row. This may be greater than
   //   w * bytes_per_pixel if there is extra padding at the end of each row
   //   (often, each row is padded to the next machine word).
   // quality: an integer in the range 0-100, where 100 is the highest quality.
-  static bool Encode(const unsigned char* input, ColorFormat format,
-                     int w, int h, int row_byte_width,
-                     int quality, std::vector<unsigned char>* output);
+  static bool Encode(const unsigned char* input,
+                     SkColorType colorType,

[dcheng, 2017/06/02 15:35:00]

Nit: color_type

From a symmetry perspective, it's a bit odd that Decode() takes a ColorFormat
while Encode() takes a SkColorType. Will we have eventual consistency here?

[scroggo_chromium, 2017/06/02 17:35:51]

Yes. We're in the process of merging Skia's decoders with Blink's, and we'd like
to use the same decoders here, too. At that point I think it makes sense to use
an SkColorType for Decode.

[msarett1, 2017/06/07 18:01:14]

Yes, I think this is a good future goal.

+                     int w,
+                     int h,
+                     int row_byte_width,
+                     int quality,
+                     std::vector<unsigned char>* output);
 
   // Decodes the JPEG data contained in input of length input_size. The
   // decoded data will be placed in *output with the dimensions in *w and *h
   // on success (returns true). This data will be written in the'format'
   // format. On failure, the values of these output variables is undefined.
   static bool Decode(const unsigned char* input, size_t input_size,
                      ColorFormat format, std::vector<unsigned char>* output,
                      int* w, int* h);
 
   // Decodes the JPEG data contained in input of length input_size. If
   // successful, a SkBitmap is created and returned.
   static std::unique_ptr<SkBitmap> Decode(const unsigned char* input,
                                           size_t input_size);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_CODEC_JPEG_CODEC_H_