Handle nested position:sticky elements correctly (compositor)

third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinderTest.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/layout/compositing/CompositingReasonFinder.h"
 
 #include "core/frame/FrameView.h"
 #include "core/layout/LayoutBlock.h"
 #include "core/layout/LayoutTestHelper.h"
 #include "core/paint/PaintLayer.h"
@@ skipping 253 matching lines @@
   EXPECT_TRUE(
       CompositingReasonFinder::requiresCompositingForEffectAnimation(*style));
 
   style->setIsRunningOpacityAnimationOnCompositor(false);
   style->setIsRunningFilterAnimationOnCompositor(false);
   style->setIsRunningBackdropFilterAnimationOnCompositor(true);
   EXPECT_TRUE(
       CompositingReasonFinder::requiresCompositingForEffectAnimation(*style));
 }
 
-TEST_F(CompositingReasonFinderTest, DoNotCompositeNestedSticky) {
+TEST_F(CompositingReasonFinderTest, CompositeNestedSticky) {
   ScopedCompositeFixedPositionForTest compositeFixedPosition(true);
 
   setBodyInnerHTML(
       "<style>.scroller { overflow: scroll; height: 200px; width: 100px; }"
       ".container { height: 500px; }"
       ".opaque { background-color: white; contain: paint; }"
       "#outerSticky { height: 50px; position: sticky; top: 0px; }"
       "#innerSticky { height: 20px; position: sticky; top: 25px; }</style>"
       "<div class='scroller'>"
       "  <div class='container'>"
       "    <div id='outerSticky' class='opaque'>"
       "      <div id='innerSticky' class='opaque'></div>"
       "    </div>"
       "  </div>"
       "</div>");
   document().view()->updateAllLifecyclePhases();
 
   Element* outerSticky = document().getElementById("outerSticky");
   PaintLayer* outerStickyLayer =
       toLayoutBoxModelObject(outerSticky->layoutObject())->layer();
   ASSERT_TRUE(outerStickyLayer);
 
   Element* innerSticky = document().getElementById("innerSticky");
   PaintLayer* innerStickyLayer =
       toLayoutBoxModelObject(innerSticky->layoutObject())->layer();
   ASSERT_TRUE(innerStickyLayer);
 
   EXPECT_EQ(PaintsIntoOwnBacking, outerStickyLayer->compositingState());
-  EXPECT_EQ(NotComposited, innerStickyLayer->compositingState());
+  EXPECT_EQ(PaintsIntoOwnBacking, innerStickyLayer->compositingState());
 }
 
 }  // namespace blink