Fix for Issue 331895: Make gesturenav screenshot greyscale

ui/gfx/codec/png_codec.h

Index: ui/gfx/codec/png_codec.h
diff --git a/ui/gfx/codec/png_codec.h b/ui/gfx/codec/png_codec.h
index abb3eaab32c952195791ff4b9684e86b2a1d5579..03347d498e61602dbccd53e98840cadfd89ab010 100644
--- a/ui/gfx/codec/png_codec.h
+++ b/ui/gfx/codec/png_codec.h
@@ -67,6 +67,8 @@ class GFX_EXPORT PNGCodec {
   //   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,
@@ -74,22 +76,26 @@ class GFX_EXPORT PNGCodec {
                      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