cc: For cc pixel test, create data url for pngs and print bounding rect.

cc/test/pixel_test_utils.cc

 // Copyright (c) 2012 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.
 
 #include "cc/test/pixel_test_utils.h"
 
 #include <string>
 #include <vector>
 
+#include "base/base64.h"
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/gfx/codec/png_codec.h"
 
 namespace cc {
 
 bool WritePNGFile(const SkBitmap& bitmap, const base::FilePath& file_path,
     bool discard_transparency) {
   std::vector<unsigned char> png_data;
   if (gfx::PNGCodec::EncodeBGRASkBitmap(bitmap,
                                         discard_transparency,
                                         &png_data) &&
       base::CreateDirectory(file_path.DirName())) {
     char* data = reinterpret_cast<char*>(&png_data[0]);
     int size = static_cast<int>(png_data.size());
     return base::WriteFile(file_path, data, size) == size;
   }
   return false;
 }
 
+std::string GetPNGDataUrl(const SkBitmap& bitmap) {
+  std::vector<unsigned char> png_data;
+  gfx::PNGCodec::EncodeBGRASkBitmap(bitmap, false, &png_data);
+  std::string data_url;
+  data_url.insert(data_url.end(), png_data.begin(), png_data.end());
+  base::Base64Encode(data_url, &data_url);
+  data_url.insert(0, "data:image/png;base64,");
+
+  return data_url;
+}
+
 bool ReadPNGFile(const base::FilePath& file_path, SkBitmap* bitmap) {
   DCHECK(bitmap);
   std::string png_data;
   return base::ReadFileToString(file_path, &png_data) &&
          gfx::PNGCodec::Decode(reinterpret_cast<unsigned char*>(&png_data[0]),
                                png_data.length(),
                                bitmap);
 }
 
 bool MatchesPNGFile(const SkBitmap& gen_bmp, base::FilePath ref_img_path,
@@ skipping 12 matching lines @@
         << "Actual: " << gen_bmp.width() << "x" << gen_bmp.height()
         << "; "
         << "Expected: " << ref_bmp.width() << "x" << ref_bmp.height();
     return false;
   }
 
   // Shortcut for empty images. They are always equal.
   if (gen_bmp.width() == 0 || gen_bmp.height() == 0)
     return true;
 
+  std::string gen_bmp_data_url = GetPNGDataUrl(gen_bmp);
+  std::string ref_bmp_data_url = GetPNGDataUrl(ref_bmp);
+  LOG(ERROR) << "Pixels do not match!";

[vmpstr, 2014/07/11 02:57:04]

Is this meant to be printed only if comparator.Compare(gen_bmp, ref_bmp) returns
false?

[sohanjg, 2014/07/11 05:15:21]

Yeah, right! its better to log it based on Compare result.
Will update, thanks!

+  LOG(ERROR) << "Actual: " << gen_bmp_data_url;
+  LOG(ERROR) << "Expected: " << ref_bmp_data_url;
+
   return comparator.Compare(gen_bmp, ref_bmp);
 }
 
 }  // namespace cc