Adding blend mode to DrawProperties

cc/trees/layer_tree_host_common.cc

Index: cc/trees/layer_tree_host_common.cc
diff --git a/cc/trees/layer_tree_host_common.cc b/cc/trees/layer_tree_host_common.cc
index 840a32b2ef4a59037f22e33e251c9edee72bc649..fe769abeb71762644153d5fcda7736861dd30e53 100644
--- a/cc/trees/layer_tree_host_common.cc
+++ b/cc/trees/layer_tree_host_common.cc
@@ -1884,6 +1884,9 @@ static void CalculateDrawPropertiesInternal(
     layer_draw_properties.screen_space_opacity_is_animating =
         animating_opacity_to_screen;
 
+    // The render surface will be responsible for applying the blend mode.
+    layer_draw_properties.blend_mode = SkXfermode::kSrcOver_Mode;
+
     render_surface->SetTargetSurfaceTransformsAreAnimating(
         animating_transform_to_target);
     render_surface->SetScreenSpaceTransformsAreAnimating(
@@ -2002,6 +2005,7 @@ static void CalculateDrawPropertiesInternal(
         animating_transform_to_screen;
     layer_draw_properties.opacity = accumulated_draw_opacity;
     layer_draw_properties.opacity_is_animating = animating_opacity_to_target;
+    layer_draw_properties.blend_mode = layer->blend_mode();
     layer_draw_properties.screen_space_opacity_is_animating =
         animating_opacity_to_screen;
     data_for_children.parent_matrix = combined_transform;