Correct for enclosing layers scroll position in sticky_data->main_thread_offset

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMappingTest.cpp

 // Copyright 2014 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/CompositedLayerMapping.h"
 
 #include "core/frame/FrameView.h"
 #include "core/layout/LayoutBoxModelObject.h"
 #include "core/layout/LayoutTestHelper.h"
 #include "core/layout/api/LayoutViewItem.h"
@@ skipping 1670 matching lines @@
   ASSERT_TRUE(sticky);
   WebLayerStickyPositionConstraint constraint =
       sticky->mainGraphicsLayer()
           ->contentLayer()
           ->layer()
           ->stickyPositionConstraint();
   EXPECT_EQ(IntPoint(0, 50),
             IntPoint(constraint.parentRelativeStickyBoxOffset));
 }
 
+TEST_P(CompositedLayerMappingTest,
+       StickyPositionIntermediateContainerContentOffset) {
+  setBodyInnerHTML(
+      "<style>.composited { will-change: transform; }"
+      "#scroller { overflow: auto; height: 200px; width: 200px; }"
+      ".container { height: 500px; }"
+      ".innerPadding { height: 10px; }"
+      "#sticky { position: sticky; top: 25px; height: 50px; }</style>"
+      "<div id='scroller' class='composited'>"
+      "<div class='composited container'>"
+      "  <div class='composited container'>"
+      "    <div class='innerPadding'></div>"
+      "    <div id='sticky' class='composited'></div>"
+      "  </div></div></div>");
+
+  CompositedLayerMapping* sticky =
+      toLayoutBlock(getLayoutObjectByElementId("sticky"))
+          ->layer()
+          ->compositedLayerMapping();
+  ASSERT_TRUE(sticky);
+
+  WebLayerStickyPositionConstraint constraint =
+      sticky->mainGraphicsLayer()
+          ->contentLayer()
+          ->layer()
+          ->stickyPositionConstraint();
+  EXPECT_EQ(IntPoint(0, 10),
+            IntPoint(constraint.parentRelativeStickyBoxOffset));
+
+  // Now scroll the page - this should not affect the parent-relative offset.
+  LayoutBoxModelObject* scroller =
+      toLayoutBoxModelObject(getLayoutObjectByElementId("scroller"));
+  PaintLayerScrollableArea* scrollableArea = scroller->getScrollableArea();
+  scrollableArea->scrollToAbsolutePosition(
+      FloatPoint(scrollableArea->scrollPosition().x(), 100));
+  ASSERT_EQ(100.0, scrollableArea->scrollPosition().y());
+
+  document().view()->updateLifecycleToCompositingCleanPlusScrolling();

[flackr, 2017/02/22 16:14:49]

Does this actually call updateStickyConstraints? We'd need to do something to
dirty them wouldn't we?

[smcgruer, 2017/02/22 18:39:04]

It appears to be:

[133571:133571:0222/133838.647623:3805035727007:INFO:CompositedLayerMappingTest.cpp(1728)]
Calling update
[133571:133571:0222/133838.647658:3805035727042:INFO:CompositedLayerMapping.cpp(295)]
CompositedLayerMapping::updateStickyConstraints for "LayoutBlockFlow DIV
id='scroller' class='composited'"
[133571:133571:0222/133838.647693:3805035727077:INFO:CompositedLayerMapping.cpp(295)]
CompositedLayerMapping::updateStickyConstraints for "LayoutBlockFlow DIV
class='composited container'"
[133571:133571:0222/133838.647718:3805035727101:INFO:CompositedLayerMapping.cpp(295)]
CompositedLayerMapping::updateStickyConstraints for "LayoutBlockFlow DIV
class='composited container'"
[133571:133571:0222/133838.647740:3805035727123:INFO:CompositedLayerMapping.cpp(295)]
CompositedLayerMapping::updateStickyConstraints for "LayoutBlockFlow (sticky
positioned) DIV id='sticky' class='composited'"
[133571:133571:0222/133838.647764:3805035727148:INFO:CompositedLayerMappingTest.cpp(1730)]
Returning from call to update

+
+  constraint = sticky->mainGraphicsLayer()
+                   ->contentLayer()
+                   ->layer()
+                   ->stickyPositionConstraint();
+  EXPECT_EQ(IntPoint(0, 10),
+            IntPoint(constraint.parentRelativeStickyBoxOffset));
+}
+
 }  // namespace blink