Don't clip contain:paint when requested to ignore clip

This fixes another place that previously forced clip for contain:paint,
causing corrupted painting in nested contain:paint containers.
Other places were fixed in https://codereview.chromium.org/1985933002.

BUG=648091
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2400063002
Cr-Commit-Position: refs/heads/master@{#423788}

third_party/WebKit/Source/core/paint/PaintLayerClipper.cpp

@@ -344,9 +344,7 @@ void PaintLayerClipper::calculateRects(
   layerBounds = LayoutRect(offset, LayoutSize(m_layer.size()));
 
   // Update the clip rects that will be passed to child layers.
-  if ((layoutObject.hasOverflowClip() ||
-       layoutObject.styleRef().containsPaint()) &&
-      shouldRespectOverflowClip(context)) {
+  if (shouldClipOverflow(context)) {
     foregroundRect.intersect(
         toLayoutBox(layoutObject)
             .overflowClipRect(offset, context.overlayScrollbarClipBehavior));
@@ -407,10 +405,9 @@ void PaintLayerClipper::calculateClipRects(const ClipRectsContext& context,
 
   adjustClipRectsForChildren(layoutObject, clipRects);
 
-  if ((layoutObject.hasOverflowClip() && shouldRespectOverflowClip(context)) ||
+  if (shouldClipOverflow(context) || layoutObject.hasClip() ||
       (layoutObject.isSVGRoot() &&
-       toLayoutSVGRoot(&layoutObject)->shouldApplyViewportClip()) ||
-      layoutObject.hasClip() || layoutObject.styleRef().containsPaint()) {
+       toLayoutSVGRoot(&layoutObject)->shouldApplyViewportClip())) {
     // This offset cannot use convertToLayerCoords, because sometimes our
     // rootLayer may be across some transformed layer boundary, for example, in
     // the PaintLayerCompositor overlapMap, where clipRects are needed in view
@@ -447,13 +444,8 @@ ClipRect PaintLayerClipper::clipRectWithGeometryMapper(
   if (properties->cssClip())
     propertyTreeState.setClip(properties->cssClip());
 
-  const LayoutObject& layoutObject = *m_layer.layoutObject();
-  if (shouldRespectOverflowClip(context) && isForeground &&
-      (layoutObject.hasOverflowClip() ||
-       layoutObject.styleRef().containsPaint())) {
-    if (properties->overflowClip())
+  if (isForeground && shouldClipOverflow(context) && properties->overflowClip())
     propertyTreeState.setClip(properties->overflowClip());
-  }
 
   const ObjectPaintProperties* ancestorProperties =
       context.rootLayer->layoutObject()->objectPaintProperties();
@@ -476,9 +468,7 @@ ClipRect PaintLayerClipper::applyOverflowClipToBackgroundRectWithGeometryMapper(
     const ClipRect& clip) const {
   const LayoutObject& layoutObject = *m_layer.layoutObject();
   FloatRect clipRect(clip.rect());
-  if ((layoutObject.hasOverflowClip() ||
-       layoutObject.styleRef().containsPaint()) &&
-      shouldRespectOverflowClip(context)) {
+  if (shouldClipOverflow(context)) {
     LayoutRect layerBoundsWithVisualOverflow =
         layoutObject.isLayoutView()
             ? toLayoutView(layoutObject).viewRect()
@@ -538,6 +528,13 @@ void PaintLayerClipper::getOrCalculateClipRects(const ClipRectsContext& context,
     calculateClipRects(context, clipRects);
 }
 
+bool PaintLayerClipper::shouldClipOverflow(
+    const ClipRectsContext& context) const {
+  return (m_layer.layoutObject()->hasOverflowClip() ||
+          m_layer.layoutObject()->styleRef().containsPaint()) &&
+         shouldRespectOverflowClip(context);
+}
+
 bool PaintLayerClipper::shouldRespectOverflowClip(
     const ClipRectsContext& context) const {
   if (&m_layer != context.rootLayer)

third_party/WebKit/Source/core/paint/PaintLayerClipper.h

@@ -210,6 +210,7 @@ class CORE_EXPORT PaintLayerClipper {
 
   void getOrCalculateClipRects(const ClipRectsContext&, ClipRects&) const;
 
+  bool shouldClipOverflow(const ClipRectsContext&) const;
   bool shouldRespectOverflowClip(const ClipRectsContext&) const;
 
   ClipRect clipRectWithGeometryMapper(const ClipRectsContext&,

third_party/WebKit/Source/core/paint/PaintLayerClipperTest.cpp

@@ -61,4 +61,60 @@ TEST_F(PaintLayerClipperTest, LayoutSVGRootChild) {
   EXPECT_EQ(LayoutRect(8, 8, 400, 0), layerBounds);
 }
 
+TEST_F(PaintLayerClipperTest, ContainPaintClip) {
+  setBodyInnerHTML(
+      "<div id='target'"
+      "    style='contain: paint; width: 200px; height: 200px; overflow: auto'>"
+      "  <div style='height: 400px'></div>"
+      "</div>");
+
+  LayoutRect infiniteRect(LayoutRect::infiniteIntRect());
+  PaintLayer* layer =
+      toLayoutBoxModelObject(getLayoutObjectByElementId("target"))->layer();
+  ClipRectsContext context(layer, PaintingClipRectsIgnoringOverflowClip);
+  LayoutRect layerBounds;
+  ClipRect backgroundRect, foregroundRect;
+  layer->clipper().calculateRects(context, infiniteRect, layerBounds,
+                                  backgroundRect, foregroundRect);
+  EXPECT_EQ(infiniteRect, backgroundRect.rect());
+  EXPECT_EQ(infiniteRect, foregroundRect.rect());
+  EXPECT_EQ(LayoutRect(0, 0, 200, 200), layerBounds);
+
+  ClipRectsContext contextClip(layer, PaintingClipRects);
+  layer->clipper().calculateRects(contextClip, infiniteRect, layerBounds,
+                                  backgroundRect, foregroundRect);
+  EXPECT_EQ(LayoutRect(0, 0, 200, 200), backgroundRect.rect());
+  EXPECT_EQ(LayoutRect(0, 0, 200, 200), foregroundRect.rect());
+  EXPECT_EQ(LayoutRect(0, 0, 200, 200), layerBounds);
+}
+
+TEST_F(PaintLayerClipperTest, NestedContainPaintClip) {
+  setBodyInnerHTML(
+      "<div style='contain: paint; width: 200px; height: 200px; overflow: "
+      "auto'>"
+      "  <div id='target' style='contain: paint; height: 400px'>"
+      "  </div>"
+      "</div>");
+
+  LayoutRect infiniteRect(LayoutRect::infiniteIntRect());
+  PaintLayer* layer =
+      toLayoutBoxModelObject(getLayoutObjectByElementId("target"))->layer();
+  ClipRectsContext context(layer->parent(),
+                           PaintingClipRectsIgnoringOverflowClip);
+  LayoutRect layerBounds;
+  ClipRect backgroundRect, foregroundRect;
+  layer->clipper().calculateRects(context, infiniteRect, layerBounds,
+                                  backgroundRect, foregroundRect);
+  EXPECT_EQ(LayoutRect(0, 0, 200, 400), backgroundRect.rect());
+  EXPECT_EQ(LayoutRect(0, 0, 200, 400), foregroundRect.rect());
+  EXPECT_EQ(LayoutRect(0, 0, 200, 400), layerBounds);
+
+  ClipRectsContext contextClip(layer->parent(), PaintingClipRects);
+  layer->clipper().calculateRects(contextClip, infiniteRect, layerBounds,
+                                  backgroundRect, foregroundRect);
+  EXPECT_EQ(LayoutRect(0, 0, 200, 200), backgroundRect.rect());
+  EXPECT_EQ(LayoutRect(0, 0, 200, 200), foregroundRect.rect());
+  EXPECT_EQ(LayoutRect(0, 0, 200, 400), layerBounds);
+}
+
 }  // namespace blink