Adding support for blending in cc::SoftwareRenderer

cc/output/renderer_pixeltest.cc

 // Copyright 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 "base/message_loop/message_loop.h"
 #include "cc/layers/append_quads_data.h"
 #include "cc/output/gl_renderer.h"
 #include "cc/quads/draw_quad.h"
 #include "cc/quads/picture_draw_quad.h"
 #include "cc/quads/texture_draw_quad.h"
@@ skipping 143 matching lines @@
                vertex_opacity,
                false);  // flipped
 }
 
 typedef ::testing::Types<GLRenderer,
                          SoftwareRenderer,
                          GLRendererWithExpandedViewport,
                          SoftwareRendererWithExpandedViewport> RendererTypes;
 TYPED_TEST_CASE(RendererPixelTest, RendererTypes);
 
-// 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) {}
-};
-
 template <typename RendererType>
 class FuzzyForSoftwareOnlyPixelComparator : public PixelComparator {
  public:
   explicit FuzzyForSoftwareOnlyPixelComparator(bool discard_alpha)
       : fuzzy_(discard_alpha), exact_(discard_alpha) {}
 
   virtual bool Compare(const SkBitmap& actual_bmp,
                        const SkBitmap& expected_bmp) const;
 
  private:
@@ skipping 2028 matching lines @@
   EXPECT_TRUE(this->RunPixelTest(
       &pass_list,
       base::FilePath(FILE_PATH_LITERAL("wrap_mode_repeat.png")),
       FuzzyPixelOffByOneComparator(true)));
 }
 
 #endif  // !defined(OS_ANDROID)
 
 }  // namespace
 }  // namespace cc