mix-blend-mode implementation for accelerated layers

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 <algorithm>
 #include <limits>
 
 #include "base/basictypes.h"
@@ skipping 591 matching lines @@
 
   gfx::Rect root_target_rect = root_layer->render_surface()->content_rect();
   float opacity = 1.f;
   SharedQuadState* shared_quad_state =
       quad_culler.UseSharedQuadState(SharedQuadState::Create());
   shared_quad_state->SetAll(root_layer->draw_transform(),
                             root_target_rect.size(),
                             root_target_rect,
                             root_target_rect,
                             false,
-                            opacity);
+                            opacity,
+                            SkXfermode::kSrcOver_Mode);
 
   AppendQuadsData append_quads_data;
 
   gfx::Transform transform_to_layer_space(gfx::Transform::kSkipInitialization);
   bool did_invert = root_layer->screen_space_transform().GetInverse(
       &transform_to_layer_space);
   DCHECK(did_invert);
   for (Region::Iterator fill_rects(screen_background_color_region);
        fill_rects.has_rect();
        fill_rects.next()) {
@@ skipping 2219 matching lines @@
   if (evicted_ui_resources_.empty())
     client_->OnCanDrawStateChanged(CanDraw());
 }
 
 void LayerTreeHostImpl::ScheduleMicroBenchmark(
     scoped_ptr<MicroBenchmarkImpl> benchmark) {
   micro_benchmark_controller_.ScheduleRun(benchmark.Pass());
 }
 
 }  // namespace cc