Fix PaintLayer::compositingContainer for self-painting non-stacked layers

third_party/WebKit/Source/core/paint/PaintLayerTest.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/PaintLayer.h"
 
 #include "core/html/HTMLIFrameElement.h"
 #include "core/layout/LayoutBoxModelObject.h"
 #include "core/layout/LayoutTestHelper.h"
 #include "core/layout/LayoutView.h"
@@ skipping 645 matching lines @@
           ->layer();
 
   // enclosingLayerWithCompositedLayerMapping is not needed or applicable to
   // SPv2.
   if (!RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
     EXPECT_EQ(compositedContainer,
               target->enclosingLayerWithCompositedLayerMapping(ExcludeSelf));
   }
 }
 
+TEST_P(PaintLayerTest, CompositingContainerSelfPaintingNonStackedFloat) {
+  setBodyInnerHTML(
+      "<div id='container' style='position: relative'>"
+      "  <span id='span' style='opacity: 0.9'>"
+      "    <div id='target' style='columns: 1; float: left'></div>"

[chrishtr, 2017/02/08 16:56:20]

Add a comment that this is testing a non-stacked, self-painting
layer.

[Xianzhu, 2017/02/09 01:21:55]

Done.

+      "  </span>"
+      "</div>");
+
+  PaintLayer* target =
+      toLayoutBoxModelObject(getLayoutObjectByElementId("target"))->layer();
+  PaintLayer* container =
+      toLayoutBoxModelObject(getLayoutObjectByElementId("container"))->layer();
+  PaintLayer* span =
+      toLayoutBoxModelObject(getLayoutObjectByElementId("span"))->layer();
+  EXPECT_EQ(container, target->containingLayer());
+  EXPECT_EQ(span, target->compositingContainer());
+}
+
 TEST_P(PaintLayerTest, ColumnSpanLayerUnderExtraLayerScrolled) {
   setBodyInnerHTML(
       "<div id='columns' style='overflow: hidden; width: 80px; height: 80px; "
       "    columns: 2; column-gap: 0'>"
       "  <div id='extraLayer'"
       "      style='position: relative; top: 100px; left: 100px'>"
       "    <div id='spanner' style='column-span: all; position: relative; "
       "        top: 50px; left: 50px'>"
       "    </div>"
       "  </div>"
@@ skipping 17 matching lines @@
   EXPECT_EQ(LayoutPoint(-150, 50), spanner->location());
   EXPECT_EQ(LayoutPoint(100, 100), extraLayer->location());
   // -60 = 2nd-column-x(40) - scroll-offset-x(200) + x-location(100)
   // 20 = y-location(100) - column-height(80)
   EXPECT_EQ(LayoutPoint(-60, 20),
             extraLayer->visualOffsetFromAncestor(columns));
   EXPECT_EQ(LayoutPoint(-150, 50), spanner->visualOffsetFromAncestor(columns));
 }
 
 }  // namespace blink