cc: Made image comparison for pixel tests error tolerant.

cc/test/pixel_test.cc

 // Copyright 2013 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.h"
 
 #include "base/path_service.h"
 #include "cc/output/compositor_frame_metadata.h"
 #include "cc/output/gl_renderer.h"
 #include "cc/output/output_surface.h"
@@ skipping 58 matching lines @@
                                  output_surface_.get(),
                                  resource_provider_.get());
 
   scoped_refptr<webkit::gpu::ContextProviderInProcess> offscreen_contexts =
       webkit::gpu::ContextProviderInProcess::Create();
   ASSERT_TRUE(offscreen_contexts->BindToCurrentThread());
   resource_provider_->set_offscreen_context_provider(offscreen_contexts);
 }
 
 bool PixelTest::PixelsMatchReference(const base::FilePath& ref_file,
-    bool discard_transparency) {
+                                     const PixelComparator& comparator) {
   gfx::Rect device_viewport_rect(device_viewport_size_);
 
   SkBitmap bitmap;
   bitmap.setConfig(SkBitmap::kARGB_8888_Config,
                    device_viewport_rect.width(),
                    device_viewport_rect.height());
   bitmap.allocPixels();
   unsigned char* pixels = static_cast<unsigned char*>(bitmap.getPixels());
   renderer_->GetFramebufferPixels(pixels, device_viewport_rect);
 
   base::FilePath test_data_dir;
   if (!PathService::Get(cc::DIR_TEST_DATA, &test_data_dir))
     return false;
 
   // To rebaseline:
   // return WritePNGFile(bitmap, test_data_dir.Append(ref_file));
 
-  return IsSameAsPNGFile(bitmap, test_data_dir.Append(ref_file),
-      discard_transparency);
+  return MatchesPNGFile(bitmap, test_data_dir.Append(ref_file), comparator);
 }
 
 }  // namespace cc