Stop clipping to visual rect bounds in PLC::CalculateBackgroundClipRect

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 494 matching lines @@
   LayoutRect layer_bounds(infinite_rect);
   ClipRect background_rect(infinite_rect);
   ClipRect foreground_rect(infinite_rect);
   target->Clipper(option).CalculateRects(context, infinite_rect, layer_bounds,
                                          background_rect, foreground_rect);
 
   EXPECT_EQ(LayoutRect(-12, -9, 124, 224), background_rect.Rect());
   EXPECT_EQ(LayoutRect(0, 0, 100, 200), foreground_rect.Rect());
 }
 
+TEST_P(PaintLayerClipperTest, CalculateBackgroundClipRectRoot) {
+  SetBodyInnerHTML(
+      "<style>"
+      "  * { margin: 0 }"
+      "  #target { "
+      " position: relative; "
+      "    overflow: hidden;"
+      "    width: 100px; height: 200px;"
+      "  }"
+      "</style>"
+      "<div id='target'></div>");
+
+  PaintLayer* target =
+      ToLayoutBoxModelObject(GetLayoutObjectByElementId("target"))->Layer();
+  ClipRectsContext context(target, kUncachedClipRects);
+  PaintLayer::GeometryMapperOption option = PaintLayer::kDoNotUseGeometryMapper;
+  if (RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled())
+    option = PaintLayer::kUseGeometryMapper;
+  ClipRect output;
+
+  target->Clipper(option).CalculateBackgroundClipRect(context, output);
+  if (RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled()) {
+    EXPECT_EQ(LayoutRect(FloatRect(LayoutRect::InfiniteIntRect())),
+              output.Rect());
+  } else {
+    EXPECT_EQ(LayoutRect(LayoutRect::InfiniteIntRect()), output.Rect());
+  }
+}
+
 }  // namespace blink