[FlexNG] Walk over anonymous objects within ScopedPaintTimingDetectorBlockPaintHook

This fixes timeouts that were occurring when FlexNG was enabled:
https://test-results.appspot.com/data/layout_results/linux-rel/292466/webkit_layout_tests%20%28with%20patch%29/layout-test-results/results.html
(*/text-with-display-style.html)

These tests timeout if they don't receive all the expected performance
entries, causing the failure (the test never completes, waiting for the
performance entries).

The specific failure for FlexNG was occurring as we didn't have a
ScopedPaintTimingDetectorBlockPaintHook for the flexbox on the stack,
only one for the anonymous block-flow. This meant that the performance
entry was never recorded for the flexbox element.

Previously the ScopedPaintTimingDetectorBlockPaintHook would get
emplaced in two different places -
 1) Within BlockPainter
 2) Within the inline painter

This changes the EmplaceIfNeeded call to walk up the layout object
tree to the first non-anonymous object which has a DOM node associated
with it.

This walk up the layout object tree should be relatively cheap. Most of
the time it will be only walking up zero or one objects.

Additionally with the layout object walk we don't need to EmplaceIfNeeded
on nested <div>s, only when we actually encounter some text to be
painted.

Bug: 845235
Change-Id: I80e18539f70d2e1df56d3d85dd928dc10a35e28e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2032428
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Steve Kobes <skobes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#739111}

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

@@ -210,19 +210,11 @@ void BlockPainter::PaintObject(const PaintInfo& paint_info,
   if (layout_block_.IsTruncated())
     return;
 
-  ScopedPaintTimingDetectorBlockPaintHook
-      scoped_paint_timing_detector_block_paint_hook;
-  if (paint_info.phase == PaintPhase::kForeground) {
-    scoped_paint_timing_detector_block_paint_hook.EmplaceIfNeeded(
-        layout_block_,
-        paint_info.context.GetPaintController().CurrentPaintChunkProperties());
-  }
   // If we're *printing or creating a paint preview of* the foreground, paint
   // the URL.
   if (paint_phase == PaintPhase::kForeground &&
-      paint_info.ShouldAddUrlMetadata()) {
+      paint_info.ShouldAddUrlMetadata())
     ObjectPainter(layout_block_).AddURLRectIfNeeded(paint_info, paint_offset);
-  }
 
   // If we're painting our background (either 1. kBlockBackground - background
   // of the current object and non-self-painting descendants, or 2.

third_party/blink/renderer/core/paint/ng/ng_box_fragment_painter.cc

@@ -1153,15 +1153,14 @@ void NGBoxFragmentPainter::PaintLineBoxChildren(
 
   ScopedPaintTimingDetectorBlockPaintHook
       scoped_paint_timing_detector_block_paint_hook;
-  const auto& layout_block = To<LayoutBlock>(*layout_object);
   if (paint_info.phase == PaintPhase::kForeground) {
     scoped_paint_timing_detector_block_paint_hook.EmplaceIfNeeded(
-        layout_block,
+        To<LayoutBoxModelObject>(*layout_object),
         paint_info.context.GetPaintController().CurrentPaintChunkProperties());
   }
 
   if (paint_info.phase == PaintPhase::kForcedColorsModeBackplate &&
-      layout_block.GetDocument().InForcedColorsMode()) {
+      layout_object->GetDocument().InForcedColorsMode()) {
     PaintBackplate(children, paint_info, paint_offset);
     return;
   }

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

@@ -335,21 +335,29 @@ ScopedPaintTimingDetectorBlockPaintHook*
     ScopedPaintTimingDetectorBlockPaintHook::top_ = nullptr;
 
 void ScopedPaintTimingDetectorBlockPaintHook::EmplaceIfNeeded(
-    const LayoutBoxModelObject& aggregator,
+    const LayoutBoxModelObject& layout_object,
     const PropertyTreeState& property_tree_state) {
-  // |reset_top_| is unset when |aggregator| is anonymous so that each
-  // aggregation corresponds to an element. See crbug.com/988593. When set,
-  // |top_| becomes |this|, and |top_| is restored to the previous value when
-  // the ScopedPaintTimingDetectorBlockPaintHook goes out of scope.
-  if (!aggregator.GetNode())
+  // Find our first non-anonymous parent.
+  const LayoutObject* object = &layout_object;
+  while (object && !object->GetNode())
+    object = object->Parent();
+
+  if (!object || !object->IsBoxModelObject())
     return;
 
+  const LayoutBoxModelObject& aggregator = To<LayoutBoxModelObject>(*object);
+  DCHECK(aggregator.GetNode());
+
+  // When set, |top_| becomes |this|, and |top_| is restored to the previous
+  // value when the ScopedPaintTimingDetectorBlockPaintHook goes out of scope.
   reset_top_.emplace(&top_, this);
+
   TextPaintTimingDetector* detector = aggregator.GetFrameView()
                                           ->GetPaintTimingDetector()
                                           .GetTextPaintTimingDetector();
+
   // Only set |data_| if we need to walk the object.
-  if (detector && detector->ShouldWalkObject(aggregator))
+  if (detector->ShouldWalkObject(aggregator))
     data_.emplace(aggregator, property_tree_state, detector);
 }