[SPv2] Add CSS mix-blend-mode support

third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp

 // Copyright 2015 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 "platform/graphics/compositing/PaintArtifactCompositor.h"
 
 #include "cc/layers/content_layer_client.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/picture_layer.h"
 #include "cc/playback/display_item_list.h"
@@ skipping 700 matching lines @@
   buildEffectNodesRecursively(nextEffect->parent());
   DCHECK_EQ(nextEffect->parent(), currentEffectNode());
 
 #if DCHECK_IS_ON()
   DCHECK(!m_effectNodesConverted.contains(nextEffect))
       << "Malformed paint artifact. Paint chunks under the same effect should "
          "be contiguous.";
   m_effectNodesConverted.add(nextEffect);
 #endif
 
+  // An effect node can't omit render surface if it has child with exotic
+  // blending mode. See comments below for more detail.
+  // TODO(crbug.com/504464): Remove premature optimization here.
+  if (nextEffect->blendMode() != SkBlendMode::kSrcOver) {
+    effectTree().Node(compositorIdForCurrentEffectNode())->has_render_surface =
+        true;
+  }
+
   // We currently create dummy layers to host effect nodes and corresponding
   // render surfaces. This should be removed once cc implements better support
   // for freestanding property trees.
   scoped_refptr<cc::Layer> dummyLayer = nextEffect->ensureDummyLayer();
   m_rootLayer->AddChild(dummyLayer);
 
   int outputClipId = compositorIdForClipNode(nextEffect->outputClip());
 
   cc::EffectNode& effectNode = *effectTree().Node(effectTree().Insert(
       cc::EffectNode(), compositorIdForCurrentEffectNode()));
   effectNode.owner_id = dummyLayer->id();
   effectNode.clip_id = outputClipId;
   // Every effect is supposed to have render surface enabled for grouping,
   // but we can get away without one if the effect is opacity-only and has only
-  // one compositing child. This is both for optimization and not introducing
-  // sub-pixel differences in layout tests.
-  // See PropertyTreeManager::switchToEffectNode() where we retrospectively
-  // enable render surface when more than one compositing child is detected.
+  // one compositing child with kSrcOver blend mode. This is both for
+  // optimization and not introducing sub-pixel differences in layout tests.
+  // See PropertyTreeManager::switchToEffectNode() and above where we
+  // retrospectively enable render surface when more than one compositing child
+  // or a child with exotic blend mode is detected.
   // TODO(crbug.com/504464): There is ongoing work in cc to delay render surface
   // decision until later phase of the pipeline. Remove premature optimization
   // here once the work is ready.
-  if (!nextEffect->filter().isEmpty())
+  if (!nextEffect->filter().isEmpty() ||
+      nextEffect->blendMode() != SkBlendMode::kSrcOver)
     effectNode.has_render_surface = true;
   effectNode.opacity = nextEffect->opacity();
   effectNode.filters = nextEffect->filter().asCcFilterOperations();
+  effectNode.blend_mode = nextEffect->blendMode();
   m_propertyTrees.effect_id_to_index_map[effectNode.owner_id] = effectNode.id;
   m_effectStack.append(BlinkEffectAndCcIdPair{nextEffect, effectNode.id});
 
   dummyLayer->set_property_tree_sequence_number(kPropertyTreeSequenceNumber);
   dummyLayer->SetTransformTreeIndex(kSecondaryRootNodeId);
   dummyLayer->SetClipTreeIndex(outputClipId);
   dummyLayer->SetEffectTreeIndex(effectNode.id);
   dummyLayer->SetScrollTreeIndex(kRealRootNodeId);
 }
 
@@ skipping 64 matching lines @@
   m_contentLayerClients.clear();
   m_contentLayerClients.swap(newContentLayerClients);
 
   // Mark the property trees as having been rebuilt.
   layerTree->property_trees()->sequence_number = kPropertyTreeSequenceNumber;
   layerTree->property_trees()->needs_rebuild = false;
   layerTree->property_trees()->ResetCachedData();
 }
 
 }  // namespace blink