mix-blend-mode implementation for accelerated layers

cc/output/renderer_pixeltest.cc

Index: cc/output/renderer_pixeltest.cc
diff --git a/cc/output/renderer_pixeltest.cc b/cc/output/renderer_pixeltest.cc
index a98ab8416afcf1b15241357b4f46c8ad70c061be..8eaabb113857a04410178493471b49d3569c1169 100644
--- a/cc/output/renderer_pixeltest.cc
+++ b/cc/output/renderer_pixeltest.cc
@@ -50,13 +50,15 @@ scoped_ptr<SharedQuadState> CreateTestSharedQuadState(
   const gfx::Rect clip_rect = rect;
   const bool is_clipped = false;
   const float opacity = 1.0f;
+  const SkXfermode::Mode blend_mode = SkXfermode::kSrcOver_Mode;
   scoped_ptr<SharedQuadState> shared_state = SharedQuadState::Create();
   shared_state->SetAll(content_to_target_transform,
                        content_bounds,
                        visible_content_rect,
                        clip_rect,
                        is_clipped,
-                       opacity);
+                       opacity,
+                       blend_mode);
   return shared_state.Pass();
 }
 
@@ -68,13 +70,15 @@ scoped_ptr<SharedQuadState> CreateTestSharedQuadStateClipped(
   const gfx::Rect visible_content_rect = clip_rect;
   const bool is_clipped = true;
   const float opacity = 1.0f;
+  const SkXfermode::Mode blend_mode = SkXfermode::kSrcOver_Mode;
   scoped_ptr<SharedQuadState> shared_state = SharedQuadState::Create();
   shared_state->SetAll(content_to_target_transform,
                        content_bounds,
                        visible_content_rect,
                        clip_rect,
                        is_clipped,
-                       opacity);
+                       opacity,
+                       blend_mode);
   return shared_state.Pass();
 }