Add the ability to write comments to PNGCodec::Encode.

tools/imagediff/image_diff.cc

Index: tools/imagediff/image_diff.cc
diff --git a/tools/imagediff/image_diff.cc b/tools/imagediff/image_diff.cc
index 4a3e3475e2bb29aa3a68bae8cd547371fba79c26..795bc98e8a7aa7685fe93381391a63eb23aa62ad 100644
--- a/tools/imagediff/image_diff.cc
+++ b/tools/imagediff/image_diff.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// 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.
 
@@ -23,6 +23,7 @@
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 #include "ui/gfx/codec/png_codec.h"
+#include "ui/gfx/size.h"
 
 #if defined(OS_WIN)
 #include "windows.h"
@@ -316,8 +317,9 @@ int DiffImages(const FilePath& file1, const FilePath& file2,
 
   std::vector<unsigned char> png_encoding;
   gfx::PNGCodec::Encode(diff_image.data(), gfx::PNGCodec::FORMAT_RGBA,
-                        diff_image.w(), diff_image.h(), diff_image.w() * 4,
-                        false, &png_encoding);
+                        gfx::Size(diff_image.w(), diff_image.h()),
+                        diff_image.w() * 4, false,
+                        std::vector<gfx::PNGCodec::Comment>(), &png_encoding);
   if (file_util::WriteFile(out_file,
       reinterpret_cast<char*>(&png_encoding.front()), png_encoding.size()) < 0)
     return kStatusError;