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

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

 // Copyright 2016 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 "core/paint/PaintLayerClipper.h"
 
 #include "core/layout/LayoutBoxModelObject.h"
 #include "core/layout/LayoutTestHelper.h"
 #include "core/layout/LayoutView.h"
 #include "core/paint/PaintLayer.h"
@@ skipping 43 matching lines @@
   LayoutRect layerBounds;
   ClipRect backgroundRect, foregroundRect;
   targetPaintLayer->clipper().calculateRects(
       context, LayoutRect(LayoutRect::infiniteIntRect()), layerBounds,
       backgroundRect, foregroundRect);
   EXPECT_EQ(LayoutRect(8, 8, 200, 300), backgroundRect.rect());
   EXPECT_EQ(LayoutRect(8, 8, 200, 300), foregroundRect.rect());
   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