Adding support for blending in cc::SoftwareRenderer

cc/test/pixel_comparator.h

 // Copyright (c) 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.
 
 #ifndef CC_TEST_PIXEL_COMPARATOR_H_
 #define CC_TEST_PIXEL_COMPARATOR_H_
 
 #include "base/compiler_specific.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 
@@ skipping 51 matching lines @@
   // Limit for percentage of pixels with a small error.
   float small_error_pixels_percentage_limit_;
   // Limit for average absolute error (excluding identical pixels).
   float avg_abs_error_limit_;
   // Limit for largest absolute error.
   int max_abs_error_limit_;
   // Threshold for small errors.
   int small_error_threshold_;
 };
 
+// All pixels can be off by one, but any more than that is an error.
+class FuzzyPixelOffByOneComparator : public FuzzyPixelComparator {
+ public:
+  explicit FuzzyPixelOffByOneComparator(bool discard_alpha)
+      : FuzzyPixelComparator(discard_alpha, 100.f, 0.f, 1.f, 1, 0) {}
+};
+
 }  // namespace cc
 
 #endif  // CC_TEST_PIXEL_COMPARATOR_H_