Revert "[CI] Combine GetBackgroundPaintLocation of PaintLayer and LayoutBoxModelObject"

This reverts commit af460e9a.

Reason for revert:
Seems to have broken paint/invalidation/table/cached-69296.html from webkit_layout_tests on Mac 10.11 - currently failed 7/7 times after this landed:
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Mac10.11%20Tests
First failing build:
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Mac10.11%20Tests/30030

Original change's description:
> [CI] Combine GetBackgroundPaintLocation of PaintLayer and LayoutBoxModelObject
> 
> For fixing SlimmingPaintV2 scrolling background painting and
> invalidation, we need a single place to get the accurate value
> of the background paint location.
> 
> Bug: 732611
> 
> Change-Id: I0ad696395d73c9c19078e13e9a32cf9dbd0c628f
> Reviewed-on: https://chromium-review.googlesource.com/c/1297586
> Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
> Reviewed-by: Robert Flack <flackr@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#602250}

TBR=flackr@chromium.org,wangxianzhu@chromium.org

Change-Id: I279520fc9deafd9891dd3a5457e42d6fa0b201aa
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 732611
Reviewed-on: https://chromium-review.googlesource.com/c/1297362Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602289}

third_party/blink/renderer/core/layout/layout_box_model_object.cc

@@ -98,30 +98,18 @@ bool LayoutBoxModelObject::UsesCompositedScrolling() const {
 }
 
 BackgroundPaintLocation LayoutBoxModelObject::GetBackgroundPaintLocation(
-    uint32_t* main_thread_scrolling_reasons) const {
-  bool may_have_scrolling_layers_without_scrolling = IsLayoutView();
-  const auto* scrollable_area = GetScrollableArea();
-  bool scrolls_overflow = scrollable_area && scrollable_area->ScrollsOverflow();
-  if (!scrolls_overflow && !may_have_scrolling_layers_without_scrolling)
-    return kBackgroundPaintInGraphicsLayer;
-
-  // If we care about LCD text, paint root backgrounds into scrolling contents
-  // layer even if style suggests otherwise. (For non-root scrollers, we just
-  // avoid compositing - see PLSA::ComputeNeedsCompositedScrolling.)
-  if (IsLayoutView()) {
-    DCHECK(Layer()->Compositor());
-    if (!Layer()->Compositor()->PreferCompositingToLCDTextEnabled())
-      return kBackgroundPaintInScrollingContents;
-  }
-
+    uint32_t* reasons) const {
+  bool has_custom_scrollbars = false;
   // TODO(flackr): Detect opaque custom scrollbars which would cover up a
   // border-box background.
-  bool has_custom_scrollbars =
-      scrollable_area &&
-      ((scrollable_area->HorizontalScrollbar() &&
-        scrollable_area->HorizontalScrollbar()->IsCustomScrollbar()) ||
-       (scrollable_area->VerticalScrollbar() &&
-        scrollable_area->VerticalScrollbar()->IsCustomScrollbar()));
+  if (PaintLayerScrollableArea* scrollable_area = GetScrollableArea()) {
+    if ((scrollable_area->HorizontalScrollbar() &&
+         scrollable_area->HorizontalScrollbar()->IsCustomScrollbar()) ||
+        (scrollable_area->VerticalScrollbar() &&
+         scrollable_area->VerticalScrollbar()->IsCustomScrollbar())) {
+      has_custom_scrollbars = true;
+    }
+  }
 
   // TODO(flackr): When we correctly clip the scrolling contents layer we can
   // paint locally equivalent backgrounds into it. https://crbug.com/645957
@@ -132,10 +120,8 @@ BackgroundPaintLocation LayoutBoxModelObject::GetBackgroundPaintLocation(
   // painting into the composited scrolling contents layer.
   // https://crbug.com/646464
   if (StyleRef().BoxShadow()) {
-    if (main_thread_scrolling_reasons) {
-      *main_thread_scrolling_reasons |=
-          MainThreadScrollingReason::kHasBoxShadowFromNonRootLayer;
-    }
+    if (reasons)
+      *reasons |= MainThreadScrollingReason::kHasBoxShadowFromNonRootLayer;
     return kBackgroundPaintInGraphicsLayer;
   }
 

third_party/blink/renderer/core/layout/layout_box_model_object.h

@@ -188,12 +188,7 @@ class CORE_EXPORT LayoutBoxModelObject : public LayoutObject {
 
   // Returns which layers backgrounds should be painted into for overflow
   // scrolling boxes.
-  // TODO(yigu): PaintLayerScrollableArea::ComputeNeedsCompositedScrolling
-  // calls this method to obtain main thread scrolling reasons due to
-  // background paint location. Once the cases get handled on compositor the
-  // parameter "reasons" could be removed.
-  BackgroundPaintLocation GetBackgroundPaintLocation(
-      uint32_t* main_thread_scrolling_reasons = nullptr) const;
+  BackgroundPaintLocation GetBackgroundPaintLocation(uint32_t* reasons) const;
 
   // These return the CSS computed padding values.
   LayoutUnit ComputedCSSPaddingTop() const {

third_party/blink/renderer/core/paint/compositing/composited_layer_mapping.cc

@@ -409,7 +409,7 @@ void CompositedLayerMapping::UpdateBackgroundPaintsOntoScrollingContentsLayer(
   // it would be visually correct and we are using composited scrolling meaning
   // we have a scrolling contents layer to paint it into.
   BackgroundPaintLocation paint_location =
-      GetLayoutObject().GetBackgroundPaintLocation();
+      owning_layer_.GetBackgroundPaintLocation();
   bool should_paint_onto_scrolling_contents_layer =
       paint_location & kBackgroundPaintInScrollingContents &&
       owning_layer_.GetScrollableArea()->UsesCompositedScrolling();
@@ -473,7 +473,7 @@ void CompositedLayerMapping::UpdateContentsOpaque() {
           owning_layer_.BackgroundIsKnownToBeOpaqueInRect(
               ToLayoutBox(GetLayoutObject()).PhysicalPaddingBoxRect()));
 
-      if (GetLayoutObject().GetBackgroundPaintLocation() &
+      if (owning_layer_.GetBackgroundPaintLocation() &
           kBackgroundPaintInGraphicsLayer) {
         graphics_layer_->SetContentsOpaque(
             owning_layer_.BackgroundIsKnownToBeOpaqueInRect(

third_party/blink/renderer/core/paint/compositing/composited_layer_mapping_test.cc

@@ -1157,21 +1157,23 @@ TEST_F(CompositedLayerMappingTest,
       true);
   SetBodyInnerHTML(R"HTML(
     <div id='container' style='overflow: scroll; width: 300px; height:
-        300px; background: white; will-change: transform;'>
-      <div style='background-color: blue; width: 2000px; height: 2000px;
-           clip-path: circle(600px at 1000px 1000px);'></div>
+    300px; background: white; will-change: transform;'>
+        <div style='background-color: blue; clip-path: circle(600px at 1000px 1000px);
+        width: 2000px; height:
+    2000px;'></div>
     </div>
   )HTML");
 
-  const auto* container = ToLayoutBox(GetLayoutObjectByElementId("container"));
+  PaintLayer* layer =
+      ToLayoutBlock(GetLayoutObjectByElementId("container"))->Layer();
   EXPECT_EQ(kBackgroundPaintInScrollingContents,
-            container->GetBackgroundPaintLocation());
+            layer->GetBackgroundPaintLocation());
 
   // We currently don't use composited scrolling when the container has a
   // border-radius so even though we can paint the background onto the scrolling
   // contents layer we don't have a scrolling contents layer to paint into in
   // this case.
-  const auto* mapping = container->Layer()->GetCompositedLayerMapping();
+  CompositedLayerMapping* mapping = layer->GetCompositedLayerMapping();
   EXPECT_FALSE(mapping->HasScrollingLayer());
   EXPECT_FALSE(mapping->BackgroundPaintsOntoScrollingContentsLayer());
 }

third_party/blink/renderer/core/paint/paint_and_raster_invalidation_test.cc

@@ -300,7 +300,7 @@ TEST_P(PaintAndRasterInvalidationTest, CompositedLayoutViewResize) {
   target->setAttribute(HTMLNames::styleAttr, "height: 2000px");
   GetDocument().View()->UpdateAllLifecyclePhases();
   EXPECT_EQ(kBackgroundPaintInScrollingContents,
-            GetLayoutView().GetBackgroundPaintLocation());
+            GetLayoutView().Layer()->GetBackgroundPaintLocation());
   const auto* mapping = GetLayoutView().Layer()->GetCompositedLayerMapping();
   EXPECT_TRUE(mapping->BackgroundPaintsOntoScrollingContentsLayer());
   EXPECT_FALSE(mapping->BackgroundPaintsOntoGraphicsLayer());
@@ -337,7 +337,7 @@ TEST_P(PaintAndRasterInvalidationTest, CompositedLayoutViewGradientResize) {
   target->setAttribute(HTMLNames::styleAttr, "height: 2000px");
   GetDocument().View()->UpdateAllLifecyclePhases();
   EXPECT_EQ(kBackgroundPaintInScrollingContents,
-            GetLayoutView().GetBackgroundPaintLocation());
+            GetLayoutView().Layer()->GetBackgroundPaintLocation());
   const auto* mapping = GetLayoutView().Layer()->GetCompositedLayerMapping();
   EXPECT_TRUE(mapping->BackgroundPaintsOntoScrollingContentsLayer());
   EXPECT_FALSE(mapping->BackgroundPaintsOntoGraphicsLayer());
@@ -386,6 +386,7 @@ TEST_P(PaintAndRasterInvalidationTest, NonCompositedLayoutViewResize) {
   EXPECT_EQ(kBackgroundPaintInScrollingContents,
             content->GetLayoutObject()
                 ->View()
+                ->Layer()
                 ->GetBackgroundPaintLocation());
 
   // Resize the content.
@@ -480,7 +481,7 @@ TEST_P(PaintAndRasterInvalidationTest,
 
   auto* target_obj = ToLayoutBoxModelObject(target->GetLayoutObject());
   EXPECT_EQ(kBackgroundPaintInScrollingContents,
-            target_obj->GetBackgroundPaintLocation());
+            target_obj->Layer()->GetBackgroundPaintLocation());
   const auto* mapping = target_obj->Layer()->GetCompositedLayerMapping();
   EXPECT_TRUE(mapping->BackgroundPaintsOntoScrollingContentsLayer());
   EXPECT_FALSE(mapping->BackgroundPaintsOntoGraphicsLayer());
@@ -550,7 +551,7 @@ TEST_P(PaintAndRasterInvalidationTest,
   LayoutBoxModelObject* target_obj =
       ToLayoutBoxModelObject(target->GetLayoutObject());
   EXPECT_EQ(kBackgroundPaintInScrollingContents,
-            target_obj->GetBackgroundPaintLocation());
+            target_obj->Layer()->GetBackgroundPaintLocation());
   const auto* mapping = target_obj->Layer()->GetCompositedLayerMapping();
   EXPECT_TRUE(mapping->BackgroundPaintsOntoScrollingContentsLayer());
   EXPECT_FALSE(mapping->BackgroundPaintsOntoGraphicsLayer());
@@ -595,8 +596,9 @@ TEST_P(PaintAndRasterInvalidationTest,
   Element* child = GetDocument().getElementById("child");
   GetDocument().View()->UpdateAllLifecyclePhases();
   EXPECT_EQ(&GetLayoutView(), object->ContainerForPaintInvalidation());
-  EXPECT_EQ(kBackgroundPaintInScrollingContents,
-            ToLayoutBoxModelObject(object)->GetBackgroundPaintLocation());
+  EXPECT_EQ(
+      kBackgroundPaintInScrollingContents,
+      ToLayoutBoxModelObject(object)->Layer()->GetBackgroundPaintLocation());
 
   // Resize the content.
   GetDocument().View()->SetTracksPaintInvalidations(true);
@@ -642,7 +644,7 @@ TEST_P(PaintAndRasterInvalidationTest, CompositedSolidBackgroundResize) {
       ToLayoutBoxModelObject(target->GetLayoutObject());
   EXPECT_EQ(
       kBackgroundPaintInScrollingContents | kBackgroundPaintInGraphicsLayer,
-      target_object->GetBackgroundPaintLocation());
+      target_object->Layer()->GetBackgroundPaintLocation());
   const auto* mapping = target_object->Layer()->GetCompositedLayerMapping();
   EXPECT_TRUE(mapping->BackgroundPaintsOntoScrollingContentsLayer());
   EXPECT_TRUE(mapping->BackgroundPaintsOntoGraphicsLayer());

third_party/blink/renderer/core/paint/paint_layer.cc

@@ -2748,6 +2748,25 @@ GraphicsLayer* PaintLayer::GraphicsLayerBacking(const LayoutObject* obj) const {
   }
 }
 
+BackgroundPaintLocation PaintLayer::GetBackgroundPaintLocation(
+    uint32_t* reasons) const {
+  BackgroundPaintLocation location;
+  bool may_have_scrolling_layers_without_scrolling = IsRootLayer();
+  if (!ScrollsOverflow() && !may_have_scrolling_layers_without_scrolling) {
+    location = kBackgroundPaintInGraphicsLayer;
+  } else {
+    // If we care about LCD text, paint root backgrounds into scrolling contents
+    // layer even if style suggests otherwise. (For non-root scrollers, we just
+    // avoid compositing - see PLSA::ComputeNeedsCompositedScrolling.)
+    DCHECK(Compositor());
+    if (IsRootLayer() && !Compositor()->PreferCompositingToLCDTextEnabled())
+      location = kBackgroundPaintInScrollingContents;
+    else
+      location = GetLayoutObject().GetBackgroundPaintLocation(reasons);
+  }
+  return location;
+}
+
 void PaintLayer::EnsureCompositedLayerMapping() {
   if (rare_data_ && rare_data_->composited_layer_mapping)
     return;

third_party/blink/renderer/core/paint/paint_layer.h

@@ -531,6 +531,12 @@ class CORE_EXPORT PaintLayer : public DisplayItemClient {
   // Returns nullptr if this PaintLayer is not composited.
   GraphicsLayer* GraphicsLayerBacking(const LayoutObject* = nullptr) const;
 
+  // TODO(yigu): PaintLayerScrollableArea::computeNeedsCompositedScrolling
+  // calls this method to obtain main thread scrolling reasons due to
+  // background paint location. Once the cases get handled on compositor the
+  // parameter "reasons" could be removed.
+  BackgroundPaintLocation GetBackgroundPaintLocation(
+      uint32_t* reasons = nullptr) const;
   // NOTE: If you are using hasCompositedLayerMapping to determine the state of
   // compositing for this layer, (and not just to do bookkeeping related to the
   // mapping like, say, allocating or deallocating a mapping), then you may have

third_party/blink/renderer/core/paint/paint_layer_scrollable_area.cc

@@ -2253,8 +2253,8 @@ bool PaintLayerScrollableArea::ComputeNeedsCompositedScrolling(
   // TODO(flackr): Allow integer transforms as long as all of the ancestor
   // transforms are also integer.
   bool background_supports_lcd_text =
-      GetLayoutBox()->StyleRef().IsStackingContext() &&
-      GetLayoutBox()->GetBackgroundPaintLocation(
+      layer->GetLayoutObject().StyleRef().IsStackingContext() &&
+      layer->GetBackgroundPaintLocation(
           &non_composited_main_thread_scrolling_reasons_) &
           kBackgroundPaintInScrollingContents &&
       layer->BackgroundIsKnownToBeOpaqueInRect(

third_party/blink/renderer/core/paint/paint_layer_scrollable_area_test.cc

@@ -45,8 +45,9 @@ class PaintLayerScrollableAreaTest : public RenderingTest {
   }
 
   BackgroundPaintLocation GetBackgroundPaintLocation(const char* element_id) {
-    return ToLayoutBoxModelObject(GetLayoutObjectByElementId(element_id))
-        ->GetBackgroundPaintLocation();
+    PaintLayer* paint_layer =
+        ToLayoutBoxModelObject(GetLayoutObjectByElementId(element_id))->Layer();
+    return paint_layer->GetBackgroundPaintLocation();
   }
 
  private: