Enable fast/images with slimming paint

Source/core/paint/LayerPainter.cpp

Index: Source/core/paint/LayerPainter.cpp
diff --git a/Source/core/paint/LayerPainter.cpp b/Source/core/paint/LayerPainter.cpp
index 4b448914adfe69fbd8df647f8ab5a00f836f9ca5..3bdd413ae59c1702df134d54dfbd574ab1876b44 100644
--- a/Source/core/paint/LayerPainter.cpp
+++ b/Source/core/paint/LayerPainter.cpp
@@ -79,47 +79,6 @@ void LayerPainter::paintLayer(GraphicsContext* context, const LayerPaintingInfo&
     paintLayerContentsAndReflection(context, paintingInfo, paintFlags);
 }
 
-class TransparencyLayerHelper {
-public:
-    TransparencyLayerHelper(GraphicsContext* context, RenderLayer& renderLayer, const RenderLayer* rootLayer, const LayoutRect& paintDirtyRect, const LayoutSize& subPixelAccumulation, PaintBehavior paintBehavior)
-        : m_transparencyLayerInProgress(false)
-        , m_context(context)
-        , m_renderLayer(renderLayer)
-    {
-        // Blending operations must be performed only with the nearest ancestor stacking context.
-        // Note that there is no need to create a transparency layer if we're painting the root.
-        // FIXME: this should be unified further into RenderLayer::paintsWithTransparency().
-        bool shouldUseTransparencyLayerForBlendMode = !renderLayer.renderer()->isDocumentElement() && renderLayer.stackingNode()->isStackingContext() && renderLayer.hasNonIsolatedDescendantWithBlendMode();
-        if (!shouldUseTransparencyLayerForBlendMode && !renderLayer.paintsWithTransparency(paintBehavior))
-            return;
-
-        OwnPtr<BeginTransparencyDisplayItem> beginTransparencyDisplayItem = adoptPtr(new BeginTransparencyDisplayItem(
-            renderLayer.renderer(), DisplayItem::BeginTransparency, renderLayer.paintingExtent(rootLayer, paintDirtyRect, subPixelAccumulation, paintBehavior),
-            renderLayer.renderer()->style()->blendMode(), renderLayer.renderer()->opacity()));
-        if (RuntimeEnabledFeatures::slimmingPaintEnabled())
-            renderLayer.renderer()->view()->viewDisplayList().add(beginTransparencyDisplayItem.release());
-        else
-            beginTransparencyDisplayItem->replay(context);
-
-        m_transparencyLayerInProgress = true;
-    }
-
-    ~TransparencyLayerHelper()
-    {
-        if (!m_transparencyLayerInProgress)
-            return;
-        OwnPtr<EndTransparencyDisplayItem> endTransparencyDisplayItem = adoptPtr(new EndTransparencyDisplayItem(m_renderLayer.renderer(), DisplayItem::EndTransparency));
-        if (RuntimeEnabledFeatures::slimmingPaintEnabled())
-            m_renderLayer.renderer()->view()->viewDisplayList().add(endTransparencyDisplayItem.release());
-        else
-            endTransparencyDisplayItem->replay(m_context);
-    }
-private:
-    bool m_transparencyLayerInProgress;
-    GraphicsContext* m_context;
-    const RenderLayer& m_renderLayer;
-};
-
 void LayerPainter::paintLayerContentsAndReflection(GraphicsContext* context, const LayerPaintingInfo& paintingInfo, PaintLayerFlags paintFlags)
 {
     ASSERT(m_renderLayer.isSelfPaintingLayer() || m_renderLayer.hasSelfPaintingLayerDescendant());
@@ -243,7 +202,16 @@ void LayerPainter::paintLayerContents(GraphicsContext* context, const LayerPaint
     // These helpers output clip and transparency layers using a RAII pattern. Stack-allocated-varibles are destructed in the reverse order of construction,
     // so they are nested properly.
     ClipPathHelper clipPathHelper(context, m_renderLayer, paintingInfo, rootRelativeBounds, rootRelativeBoundsComputed, offsetFromRoot, paintFlags);
-    TransparencyLayerHelper transparencyLayerHelper(context, m_renderLayer, paintingInfo.rootLayer, paintingInfo.paintDirtyRect, paintingInfo.subPixelAccumulation, paintingInfo.paintBehavior);
+
+    OwnPtr<TransparencyRecorder> transparencyRecorder;
+    // Blending operations must be performed only with the nearest ancestor stacking context.
+    // Note that there is no need to create a transparency layer if we're painting the root.
+    // FIXME: this should be unified further into RenderLayer::paintsWithTransparency().
+    bool shouldUseTransparencyLayerForBlendMode = !m_renderLayer.renderer()->isDocumentElement() && m_renderLayer.stackingNode()->isStackingContext() && m_renderLayer.hasNonIsolatedDescendantWithBlendMode();
+    if (shouldUseTransparencyLayerForBlendMode || m_renderLayer.paintsWithTransparency(paintingInfo.paintBehavior)) {
+        transparencyRecorder = adoptPtr(new TransparencyRecorder(context, m_renderLayer.renderer(), DisplayItem::BeginTransparency, m_renderLayer.paintingExtent(paintingInfo.rootLayer, paintingInfo.paintDirtyRect,

[pdr., 2014/11/21 20:09:05]

What do you think about emiting a clip here with the clip recorder instead of
baking it into the transparency recorder?

+            paintingInfo.subPixelAccumulation, paintingInfo.paintBehavior), m_renderLayer.renderer()->style()->blendMode(), m_renderLayer.renderer()->opacity()));
+    }
 
     LayerPaintingInfo localPaintingInfo(paintingInfo);