mix-blend-mode implementation for accelerated layers - blink part

Source/core/rendering/RenderLayerBacking.cpp

Index: Source/core/rendering/RenderLayerBacking.cpp
diff --git a/Source/core/rendering/RenderLayerBacking.cpp b/Source/core/rendering/RenderLayerBacking.cpp
index 991d529755e2b4362627f51818ffca24254383f2..2411ccbc897b6b331cb790a8cd41c0f52fc12ba2 100644
--- a/Source/core/rendering/RenderLayerBacking.cpp
+++ b/Source/core/rendering/RenderLayerBacking.cpp
@@ -208,6 +208,8 @@ void RenderLayerBacking::createPrimaryGraphicsLayer()
 
     if (RuntimeEnabledFeatures::cssCompositingEnabled())
         updateLayerBlendMode(renderer()->style());
+    if (RuntimeEnabledFeatures::cssCompositingEnabled())
+        updateIsolatedGroupRoot();
 }
 
 void RenderLayerBacking::destroyGraphicsLayers()
@@ -263,8 +265,16 @@ void RenderLayerBacking::updateFilters(const RenderStyle* style)
     }
 }
 
-void RenderLayerBacking::updateLayerBlendMode(const RenderStyle*)
+void RenderLayerBacking::updateLayerBlendMode(const RenderStyle* style)
 {
+    setBlendMode(style->blendMode());
+}
+
+void RenderLayerBacking::updateIsolatedGroupRoot()
+{
+    const RenderLayer* layer = m_owningLayer;
+    ASSERT(!layer->shouldIsolateCompositedBlendingDescendants() || layer->isStackingContext());
+    childForSuperlayers()->setIsIsolatedGroupRoot(layer->shouldIsolateCompositedBlendingDescendants());
 }
 
 void RenderLayerBacking::updateContentsOpaque()
@@ -493,6 +503,8 @@ void RenderLayerBacking::updateGraphicsLayerGeometry()
 
     if (RuntimeEnabledFeatures::cssCompositingEnabled())
         updateLayerBlendMode(renderer()->style());
+    if (RuntimeEnabledFeatures::cssCompositingEnabled())
+        updateIsolatedGroupRoot();
 
     bool isSimpleContainer = isSimpleContainerCompositingLayer();
 
@@ -1463,8 +1475,9 @@ void RenderLayerBacking::setRequiresOwnBackingStore(bool requiresOwnBacking)
     compositor()->repaintInCompositedAncestor(m_owningLayer, compositedBounds());
 }
 
-void RenderLayerBacking::setBlendMode(BlendMode)
+void RenderLayerBacking::setBlendMode(BlendMode blendMode)
 {
+    childForSuperlayers()->setBlendMode(blendMode);
 }
 
 void RenderLayerBacking::setContentsNeedDisplay()