[BlinkGenPropertyTrees] Fix under-invalidation of backface-visibility

Backface visibility does not depend on having a PaintLayer but the
invalidation logic did. This patch extracts out the invalidation of
paint properties into LayoutBoxModelObject::StyleDidChange. This patch
also removes outdated code that caused repaints for backface visibility
changes.

Bug: 946541
Change-Id: Ib6790b9c7d442d8e8971185c2eda2a99f10e8506
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1553168Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Commit-Queue: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#648263}

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

@@ -437,30 +437,30 @@ void LayoutBoxModelObject::StyleDidChange(StyleDifference diff,
     }
   }
 
-  if (old_style && HasLayer() && !Layer()->NeedsRepaint()) {
-    if (old_style->BackfaceVisibility() != StyleRef().BackfaceVisibility()) {
-      // We need to repaint the layer to update the backface visibility value of
-      // the paint chunk.
+  if (old_style &&
+      old_style->BackfaceVisibility() != StyleRef().BackfaceVisibility()) {
+    SetNeedsPaintPropertyUpdate();
+  }
+
+  if (old_style && HasLayer() && !Layer()->NeedsRepaint() &&
+      diff.TransformChanged() &&
+      (RuntimeEnabledFeatures::CompositeAfterPaintEnabled() ||
+       !Layer()->HasStyleDeterminedDirectCompositingReasons())) {
+    // PaintLayerPainter::PaintLayerWithAdjustedRoot skips painting of a layer
+    // whose transform is not invertible, so we need to repaint the layer when
+    // invertible status changes.
+    TransformationMatrix old_transform;
+    TransformationMatrix new_transform;
+    old_style->ApplyTransform(
+        old_transform, LayoutSize(), ComputedStyle::kExcludeTransformOrigin,
+        ComputedStyle::kExcludeMotionPath,
+        ComputedStyle::kIncludeIndependentTransformProperties);
+    StyleRef().ApplyTransform(
+        new_transform, LayoutSize(), ComputedStyle::kExcludeTransformOrigin,
+        ComputedStyle::kExcludeMotionPath,
+        ComputedStyle::kIncludeIndependentTransformProperties);
+    if (old_transform.IsInvertible() != new_transform.IsInvertible())
       Layer()->SetNeedsRepaint();
-    } else if (diff.TransformChanged() &&
-               (RuntimeEnabledFeatures::CompositeAfterPaintEnabled() ||
-                !Layer()->HasStyleDeterminedDirectCompositingReasons())) {
-      // PaintLayerPainter::PaintLayerWithAdjustedRoot skips painting of a layer
-      // whose transform is not invertible, so we need to repaint the layer when
-      // invertible status changes.
-      TransformationMatrix old_transform;
-      TransformationMatrix new_transform;
-      old_style->ApplyTransform(
-          old_transform, LayoutSize(), ComputedStyle::kExcludeTransformOrigin,
-          ComputedStyle::kExcludeMotionPath,
-          ComputedStyle::kIncludeIndependentTransformProperties);
-      StyleRef().ApplyTransform(
-          new_transform, LayoutSize(), ComputedStyle::kExcludeTransformOrigin,
-          ComputedStyle::kExcludeMotionPath,
-          ComputedStyle::kIncludeIndependentTransformProperties);
-      if (old_transform.IsInvertible() != new_transform.IsInvertible())
-        Layer()->SetNeedsRepaint();
-    }
   }
 }
 

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

@@ -1688,4 +1688,13 @@ TEST_P(PaintPropertyTreeUpdateTest, ChangeDuringAnimation) {
   EXPECT_TRUE(paint_artifact_compositor->NeedsUpdate());
 }
 
+TEST_P(PaintPropertyTreeUpdateTest, BackfaceVisibilityInvalidatesProperties) {
+  SetBodyInnerHTML("<span id='span'>a</span>");
+
+  auto* span = GetDocument().getElementById("span");
+  span->setAttribute(html_names::kStyleAttr, "backface-visibility: hidden;");
+  GetDocument().View()->UpdateLifecycleToLayoutClean();
+  EXPECT_TRUE(span->GetLayoutObject()->NeedsPaintPropertyUpdate());
+}
+
 }  // namespace blink