[Blink] Clean-up CompositingInputsUpdater

This CL does some light clean-up to CompositingInputsUpdater.
It is for aesthetic improvement only and should not change behavior.

1. Move AncestorDependentCompositingInputs computation to its own helper
   function.
2. Remove CompositingInputsUpdater::AncestorInfo::has_ancestor_with_clip_path
   which is unused.
3. Add shorthand variable layout_object = layer->GetLayoutObject().

Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: I745a392b80adedef278fa5ad45436b2c652bf37d
Reviewed-on: https://chromium-review.googlesource.com/950008
Commit-Queue: Tien-Ren Chen <trchen@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541248}

third_party/WebKit/Source/core/paint/compositing/CompositingInputsUpdater.cpp

@@ -91,10 +91,12 @@ void CompositingInputsUpdater::UpdateRecursive(PaintLayer* layer,
       update_type != kForceUpdate)
     return;
 
+  LayoutBoxModelObject& layout_object = layer->GetLayoutObject();
+
   const PaintLayer* previous_overflow_layer = layer->AncestorOverflowLayer();
   layer->UpdateAncestorOverflowLayer(info.last_overflow_clip_layer);
   if (info.last_overflow_clip_layer && layer->NeedsCompositingInputsUpdate() &&
-      layer->GetLayoutObject().Style()->HasStickyConstrainedPosition()) {
+      layout_object.Style()->HasStickyConstrainedPosition()) {
     if (!RuntimeEnabledFeatures::RootLayerScrollingEnabled()) {
       if (info.last_overflow_clip_layer != previous_overflow_layer) {
         // Old ancestor scroller should no longer have these constraints.
@@ -107,21 +109,17 @@ void CompositingInputsUpdater::UpdateRecursive(PaintLayer* layer,
         // If our ancestor scroller has changed and the previous one was the
         // root layer, we are no longer viewport constrained.
         if (previous_overflow_layer && previous_overflow_layer->IsRootLayer()) {
-          layer->GetLayoutObject()
-              .View()
-              ->GetFrameView()
-              ->RemoveViewportConstrainedObject(layer->GetLayoutObject());
+          layout_object.View()->GetFrameView()->RemoveViewportConstrainedObject(
+              layout_object);
         }
       }
 
       if (info.last_overflow_clip_layer->IsRootLayer()) {
-        layer->GetLayoutObject()
-            .View()
-            ->GetFrameView()
-            ->AddViewportConstrainedObject(layer->GetLayoutObject());
+        layout_object.View()->GetFrameView()->AddViewportConstrainedObject(
+            layout_object);
       }
     }
-    layer->GetLayoutObject().UpdateStickyPositionConstraints();
+    layout_object.UpdateStickyPositionConstraints();
 
     // Sticky position constraints and ancestor overflow scroller affect
     // the sticky layer position, so we need to update it again here.
@@ -133,21 +131,66 @@ void CompositingInputsUpdater::UpdateRecursive(PaintLayer* layer,
 
   geometry_map_.PushMappingsToAncestor(layer, layer->Parent());
 
-  if (layer->HasCompositedLayerMapping())
-    info.enclosing_composited_layer = layer;
-
+  PaintLayer* enclosing_composited_layer =
+      layer->HasCompositedLayerMapping() ? layer
+                                         : info.enclosing_composited_layer;
   if (layer->NeedsCompositingInputsUpdate()) {
-    if (info.enclosing_composited_layer) {
-      info.enclosing_composited_layer->GetCompositedLayerMapping()
+    if (enclosing_composited_layer) {
+      enclosing_composited_layer->GetCompositedLayerMapping()
           ->SetNeedsGraphicsLayerUpdate(kGraphicsLayerUpdateSubtree);
     }
     update_type = kForceUpdate;
   }
 
-  if (update_type == kForceUpdate) {
+  if (update_type == kForceUpdate)
+    UpdateAncestorDependentCompositingInputs(layer, info);
+
+  info.enclosing_composited_layer = enclosing_composited_layer;
+
+  if (layer->StackingNode()->IsStackingContext())
+    info.ancestor_stacking_context = layer;
+
+  if (layer->IsRootLayer() || layout_object.HasOverflowClip())
+    info.last_overflow_clip_layer = layer;
+
+  if (layer->ScrollsOverflow())
+    info.last_scrolling_ancestor = layer;
+
+  if (layout_object.HasClipRelatedProperty())
+    info.has_ancestor_with_clip_related_property = true;
+
+  for (PaintLayer* child = layer->FirstChild(); child;
+       child = child->NextSibling())
+    UpdateRecursive(child, update_type, info);
+
+  layer->DidUpdateCompositingInputs();
+
+  geometry_map_.PopMappingsToAncestor(layer->Parent());
+
+  if (layer->SelfPaintingStatusChanged()) {
+    layer->ClearSelfPaintingStatusChanged();
+    // If the floating object becomes non-self-painting, so some ancestor should
+    // paint it; if it becomes self-painting, it should paint itself and no
+    // ancestor should paint it.
+    if (layout_object.IsFloating()) {
+      LayoutBlockFlow::UpdateAncestorShouldPaintFloatingObject(
+          *layer->GetLayoutBox());
+    }
+  }
+}
+
+void CompositingInputsUpdater::UpdateAncestorDependentCompositingInputs(
+    PaintLayer* layer,
+    const AncestorInfo& info) {
+  if (layer->IsRootLayer()) {
+    layer->UpdateAncestorDependentCompositingInputs(
+        PaintLayer::AncestorDependentCompositingInputs());
+    return;
+  }
+
   PaintLayer::AncestorDependentCompositingInputs properties;
+  LayoutBoxModelObject& layout_object = layer->GetLayoutObject();
 
-    if (!layer->IsRootLayer()) {
   if (!RuntimeEnabledFeatures::SlimmingPaintV2Enabled()) {
     properties.unclipped_absolute_bounding_box =
         EnclosingIntRect(geometry_map_.AbsoluteRect(
@@ -180,9 +223,8 @@ void CompositingInputsUpdater::UpdateRecursive(PaintLayer* layer,
       parent->IsTransparent() ? parent : parent->OpacityAncestor();
   properties.transform_ancestor =
       parent->Transform() ? parent : parent->TransformAncestor();
-      properties.filter_ancestor = parent->HasFilterInducingProperty()
-                                       ? parent
-                                       : parent->FilterAncestor();
+  properties.filter_ancestor =
+      parent->HasFilterInducingProperty() ? parent : parent->FilterAncestor();
   properties.clip_path_ancestor = parent->GetLayoutObject().HasClipPath()
                                       ? parent
                                       : parent->ClipPathAncestor();
@@ -190,7 +232,7 @@ void CompositingInputsUpdater::UpdateRecursive(PaintLayer* layer,
       parent->GetLayoutObject().HasMask() ? parent : parent->MaskAncestor();
 
   bool layer_is_fixed_position =
-          layer->GetLayoutObject().Style()->GetPosition() == EPosition::kFixed;
+      layout_object.Style()->GetPosition() == EPosition::kFixed;
 
   properties.nearest_fixed_position_layer =
       layer_is_fixed_position ? layer : parent->NearestFixedPositionLayer();
@@ -209,10 +251,10 @@ void CompositingInputsUpdater::UpdateRecursive(PaintLayer* layer,
             : parent_layer_on_clipping_container_chain->ClippingContainer();
 
     if (!layer->SubtreeIsInvisible()) {
-          if (layer->GetLayoutObject().IsOutOfFlowPositioned() &&
+      if (layout_object.IsOutOfFlowPositioned() &&
           NeedsToEscapeClipInheritedFromCompositingContainer(
-                  layer, parent_layer_on_clipping_container_chain
-                             ->GetLayoutObject())) {
+              layer,
+              parent_layer_on_clipping_container_chain->GetLayoutObject())) {
         properties.clip_parent = parent_layer_on_clipping_container_chain;
       } else if (parent_layer_on_clipping_container_chain
                      ->CompositingContainer() ==
@@ -234,8 +276,7 @@ void CompositingInputsUpdater::UpdateRecursive(PaintLayer* layer,
   }
 
   if (info.last_scrolling_ancestor) {
-        const LayoutObject* containing_block =
-            layer->GetLayoutObject().ContainingBlock();
+    const LayoutObject* containing_block = layout_object.ContainingBlock();
     const PaintLayer* parent_layer_on_containing_block_chain =
         FindParentLayerOnContainingBlockChain(containing_block);
 
@@ -252,41 +293,8 @@ void CompositingInputsUpdater::UpdateRecursive(PaintLayer* layer,
             &properties.ancestor_scrolling_layer->GetLayoutObject()))
       properties.scroll_parent = properties.ancestor_scrolling_layer;
   }
-    }
 
   layer->UpdateAncestorDependentCompositingInputs(properties);
-  }
-
-  if (layer->StackingNode()->IsStackingContext())
-    info.ancestor_stacking_context = layer;
-
-  if (layer->IsRootLayer() || layer->GetLayoutObject().HasOverflowClip())
-    info.last_overflow_clip_layer = layer;
-
-  if (layer->ScrollsOverflow())
-    info.last_scrolling_ancestor = layer;
-
-  if (layer->GetLayoutObject().HasClipRelatedProperty())
-    info.has_ancestor_with_clip_related_property = true;
-
-  for (PaintLayer* child = layer->FirstChild(); child;
-       child = child->NextSibling())
-    UpdateRecursive(child, update_type, info);
-
-  layer->DidUpdateCompositingInputs();
-
-  geometry_map_.PopMappingsToAncestor(layer->Parent());
-
-  if (layer->SelfPaintingStatusChanged()) {
-    layer->ClearSelfPaintingStatusChanged();
-    // If the floating object becomes non-self-painting, so some ancestor should
-    // paint it; if it becomes self-painting, it should paint itself and no
-    // ancestor should paint it.
-    if (layer->GetLayoutObject().IsFloating()) {
-      LayoutBlockFlow::UpdateAncestorShouldPaintFloatingObject(
-          *layer->GetLayoutBox());
-    }
-  }
 }
 
 #if DCHECK_IS_ON()

third_party/WebKit/Source/core/paint/compositing/CompositingInputsUpdater.h

@@ -49,10 +49,11 @@ class CompositingInputsUpdater {
     // containing block chain.
     PaintLayer* last_scrolling_ancestor;
     bool has_ancestor_with_clip_related_property;
-    bool has_ancestor_with_clip_path;
   };
 
   void UpdateRecursive(PaintLayer*, UpdateType, AncestorInfo);
+  void UpdateAncestorDependentCompositingInputs(PaintLayer*,
+                                                const AncestorInfo&);
 
   LayoutGeometryMap geometry_map_;
   PaintLayer* root_layer_;