Fix for Issue 331895: Make gesturenav screenshot greyscale

ui/gfx/codec/png_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_PNG_CODEC_H_
 #define UI_GFX_CODEC_PNG_CODEC_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 49 matching lines @@
   // multiplied.
   //
   // size: 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).
   // discard_transparency: when true, and when the input data format includes
   //   alpha values, these alpha values will be discarded and only RGB will be
   //   written to the resulting file. Otherwise, alpha values in the input
   //   will be preserved.
+  // discard_color: when true, color images will be converted to grayscale
+  //   (can be used in combination with discard_transparency)
   // comments: comments to be written in the png's metadata.
   static bool Encode(const unsigned char* input,
                      ColorFormat format,
                      const Size& size,
                      int row_byte_width,
                      bool discard_transparency,
                      const std::vector<Comment>& comments,
-                     std::vector<unsigned char>* output);
+                     std::vector<unsigned char>* output,
+                     bool discard_color = false);

[sadrul, 2014/01/15 21:43:06]

default parameter values are not allowed in chromium style guide

 
   // Call PNGCodec::Encode on the supplied SkBitmap |input|, which is assumed
-  // to be BGRA, 32 bits per pixel. The params |discard_transparency| and
-  // |output| are passed directly to Encode; refer to Encode for more
-  // information. During the call, an SkAutoLockPixels lock is held on |input|.
+  // to be BGRA, 32 bits per pixel. The params |discard_transparency|,
+  // |discard_color|, and |output| are passed directly to Encode; refer to
+  // Encode for more information. During the call, an SkAutoLockPixels lock
+  // is held on |input|.
   static bool EncodeBGRASkBitmap(const SkBitmap& input,
                                  bool discard_transparency,
-                                 std::vector<unsigned char>* output);
+                                 std::vector<unsigned char>* output,
+                                 bool discard_color = false);
 
   // Call PNGCodec::Encode on the supplied SkBitmap |input|. The difference
   // between this and the previous method is that this restricts compression to
   // zlib q1, which is just rle encoding.
   static bool FastEncodeBGRASkBitmap(const SkBitmap& input,
                                      bool discard_transparency,
-                                     std::vector<unsigned char>* output);
+                                     std::vector<unsigned char>* output,
+                                     bool discard_color = false);
 
   // Decodes the PNG 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 are undefined.
   //
   // This function may not support all PNG types, and it hasn't been tested
   // with a large number of images, so assume a new format may not work. It's
   // really designed to be able to read in something written by Encode() above.
   static bool Decode(const unsigned char* input, size_t input_size,
@@ skipping 11 matching lines @@
   static bool Decode(const unsigned char* input, size_t input_size,
                      SkBitmap* bitmap);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PNGCodec);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_CODEC_PNG_CODEC_H_