stop using SkXfermode -- use SkBlendMode instead

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 713 matching lines @@
   // TODO(danakj): Make the gutter quads generated by the solid color layer
   // (make it smarter about generating quads to fill unoccluded areas).
 
   gfx::Rect root_target_rect = root_render_surface->content_rect();
   float opacity = 1.f;
   int sorting_context_id = 0;
   SharedQuadState* shared_quad_state =
       target_render_pass->CreateAndAppendSharedQuadState();
   shared_quad_state->SetAll(gfx::Transform(), root_target_rect.size(),
                             root_target_rect, root_target_rect, false, opacity,
-                            SkXfermode::kSrcOver_Mode, sorting_context_id);
+                            SkBlendMode::kSrcOver, sorting_context_id);
 
   for (Region::Iterator fill_rects(fill_region); fill_rects.has_rect();
        fill_rects.next()) {
     gfx::Rect screen_space_rect = fill_rects.rect();
     gfx::Rect visible_screen_space_rect = screen_space_rect;
     // Skip the quad culler and just append the quads directly to avoid
     // occlusion checks.
     SolidColorDrawQuad* quad =
         target_render_pass->CreateAndAppendDrawQuad<SolidColorDrawQuad>();
     quad->SetNew(shared_quad_state, screen_space_rect,
@@ skipping 3335 matching lines @@
       worker_context_visibility_ =
           worker_context->CacheController()->ClientBecameVisible();
     } else {
       worker_context->CacheController()->ClientBecameNotVisible(
           std::move(worker_context_visibility_));
     }
   }
 }
 
 }  // namespace cc