Revert "IO: Use pre-margin target rect for an empty check for intersection threshold"

This reverts commit 258f8486.

Reason for revert: failure in browser_tests/TabStripTabListTest.All

As unlikely as it looks (to me), I've bisected test failure to this CL

Builder Linux Tests (dbg)(1): https://ci.chromium.org/p/chromium/builders/ci/Linux%20Tests%20%28dbg%29%281%29

Original change's description:
> IO: Use pre-margin target rect for an empty check for intersection threshold
>
> This patch ensures that we use a pre-margin version of the target rect
> if we are checking whether it was empty. This is to make sure that we
> compute a "1" intersection ratio in cases where an ancestor of a
> margin-padded target causes it to be empty.
>
> In this case, we should report 1 intersection, because we are intersecting
> and target is an empty rect. However, because we padded the target
> with a margin, we ended up doing the wrong check and ultimately compute
> 0 intersection in a different conditional branch (before this patch).
>
> This patch restores correct behavior.
>
> R=​szager@chromium.org, chrishtr@chromium.org
> Fixed: 1156815
>
> Change-Id: I1697388dd127737a0203d1c3ff15095de4ab41df
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2580046
> Reviewed-by: Stefan Zager <szager@chromium.org>
> Commit-Queue: vmpstr <vmpstr@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#834930}

TBR=szager@chromium.org,vmpstr@chromium.org,chrishtr@chromium.org,chromium-scoped@luci-project-accounts.iam.gserviceaccount.com

Change-Id: Idf7927cbd535d91db51da4f3f97280c2359e9b97
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2582059Reviewed-by: Thiemo Nagel <tnagel@chromium.org>
Commit-Queue: Thiemo Nagel <tnagel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#835216}

third_party/blink/renderer/core/intersection_observer/intersection_geometry.cc

@@ -97,27 +97,24 @@ PhysicalRect InitializeRootRect(const LayoutObject* root,
   return result;
 }
 
-// Return the bounding box of target in target's own coordinate system, also
-// return a bool indicating whether the target rect before margin application
-// was empty.
-std::pair<PhysicalRect, bool> InitializeTargetRect(const LayoutObject* target,
-                                                   unsigned flags,
-                                                   const Vector<Length>& margin,
-                                                   const LayoutObject* root) {
-  std::pair<PhysicalRect, bool> result;
+// Return the bounding box of target in target's own coordinate system
+PhysicalRect InitializeTargetRect(const LayoutObject* target,
+                                  unsigned flags,
+                                  const Vector<Length>& margin,
+                                  const LayoutObject* root) {
+  PhysicalRect result;
   if ((flags & IntersectionGeometry::kShouldUseReplacedContentRect) &&
       target->IsLayoutEmbeddedContent()) {
-    result.first = To<LayoutEmbeddedContent>(target)->ReplacedContentRect();
+    result = To<LayoutEmbeddedContent>(target)->ReplacedContentRect();
   } else if (target->IsBox()) {
-    result.first = PhysicalRect(To<LayoutBox>(target)->BorderBoundingBox());
+    result = PhysicalRect(To<LayoutBox>(target)->BorderBoundingBox());
   } else if (target->IsLayoutInline()) {
-    result.first = target->AbsoluteToLocalRect(
+    result = target->AbsoluteToLocalRect(
         PhysicalRect::EnclosingRect(target->AbsoluteBoundingBoxFloatRect()));
   } else {
-    result.first = To<LayoutText>(target)->PhysicalLinesBoundingBox();
+    result = To<LayoutText>(target)->PhysicalLinesBoundingBox();
   }
-  result.second = result.first.IsEmpty();
-  ApplyMargin(result.first, margin, root->StyleRef().EffectiveZoom(),
+  ApplyMargin(result, margin, root->StyleRef().EffectiveZoom(),
               InitializeRootRect(root, {} /* margin */));
   return result;
 }
@@ -296,30 +293,22 @@ void IntersectionGeometry::ComputeGeometry(const RootGeometry& root_geometry,
   //   root_rect_ is in root's coordinate system
   //   The coordinate system for unclipped_intersection_rect_ depends on whether
   //       or not we can use previously cached geometry...
-  bool pre_margin_target_rect_is_empty;
   if (ShouldUseCachedRects()) {
     target_rect_ = cached_rects->local_target_rect;
-    pre_margin_target_rect_is_empty =
-        cached_rects->pre_margin_target_rect_is_empty;
-
     // The cached intersection rect has already been mapped/clipped up to the
     // root, except that the root's scroll offset and overflow clip have not
     // been applied.
     unclipped_intersection_rect_ =
         cached_rects->unscrolled_unclipped_intersection_rect;
   } else {
-    std::tie(target_rect_, pre_margin_target_rect_is_empty) =
-        InitializeTargetRect(target, flags_, target_margin, root);
+    target_rect_ = InitializeTargetRect(target, flags_, target_margin, root);
     // We have to map/clip target_rect_ up to the root, so we begin with the
     // intersection rect in target's coordinate system. After ClipToRoot, it
     // will be in root's coordinate system.
     unclipped_intersection_rect_ = target_rect_;
   }
-  if (cached_rects) {
+  if (cached_rects)
     cached_rects->local_target_rect = target_rect_;
-    cached_rects->pre_margin_target_rect_is_empty =
-        pre_margin_target_rect_is_empty;
-  }
   root_rect_ = root_geometry.local_root_rect;
 
   bool does_intersect =
@@ -409,14 +398,7 @@ void IntersectionGeometry::ComputeGeometry(const RootGeometry& root_geometry,
   if (does_intersect) {
     const PhysicalRect& comparison_rect =
         ShouldTrackFractionOfRoot() ? root_rect_ : target_rect_;
-    // Note that if we are checking whether target is empty, we have to use
-    // pre_margin_target_rect_is_empty for the check. This is because if we are
-    // using target margin, we may have inflated the rect, so direct empty check
-    // will be wrong.
-    bool comparison_rect_empty = ShouldTrackFractionOfRoot()
-                                     ? root_rect_.IsEmpty()
-                                     : pre_margin_target_rect_is_empty;
-    if (comparison_rect_empty) {
+    if (comparison_rect.IsEmpty()) {
       intersection_ratio_ = 1;
     } else {
       const PhysicalSize& intersection_size = intersection_rect_.size;

third_party/blink/renderer/core/intersection_observer/intersection_geometry.h

@@ -63,8 +63,6 @@ class CORE_EXPORT IntersectionGeometry {
     // True iff unscrolled_unclipped_intersection_rect actually intersects the
     // root, as defined by edge-inclusive intersection rules.
     bool does_intersect;
-    // True iff the target rect before any margins were applied was empty
-    bool pre_margin_target_rect_is_empty;
     // Invalidation flag
     bool valid;
   };

third_party/blink/web_tests/external/wpt/css/css-contain/content-visibility/content-visibility-079-ref.html

-<!doctype HTML>
-<html>
-<meta charset="utf8">
-<title>CSS Content Visibility: auto in overflow hidden paints (reference)</title>
-<link rel="author" title="Vladimir Levin" href="mailto:vmpstr@chromium.org">
-<link rel="help" href="https://drafts.csswg.org/css-contain/#content-visibility">
-
-<div>content</div>

third_party/blink/web_tests/external/wpt/css/css-contain/content-visibility/content-visibility-079.html

-<!doctype HTML>
-<meta charset="utf8">
-<title>CSS Content Visibility: auto in overflow hidden paints</title>
-<link rel="author" title="Vladimir Levin" href="mailto:vmpstr@chromium.org">
-<link rel="help" href="https://drafts.csswg.org/css-contain/#content-visibility">
-<link rel="match" href="content-visibility-079-ref.html">
-<meta name="assert" content="content-visibility auto element paints in an overflow hidden element that is not sized">
-
-<style>
-.auto { content-visibility: auto; }
-.overflow { overflow: hidden; }
-</style>
-
-<div class=overflow>
-  <div class=auto>content</div>
-</div>