ruby: Secure text height even if ruby base is empty

New behavior matches to Firefox.

Implementation:
Layout(NG)RubyBase is always created just after a Layout(NG)RubyRun is
created, by calling LayoutRubyRun::RubyBaseSafe().
Set |-internal-empty-line-height:fabricated| to keep one line height and
put a ruby annotation on it.

- RubyBase existence check does not make sense any longer. Code like
  |if (HasRubyBase())...| should be |if (RubyBase()->FirstChild()) ...|.
- We need some changes in order to avoid removing empty RubyBase.

Test:
* ruby-base-different-size.html:
  It passed accidentally. It fails now due to a wrong base:annotation
  matching.

Bug: 847274
Change-Id: I46711c1433e9e154fc75346d4c40acf4c2bcaa02
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3636540
Reviewed-by: Koji Ishii <kojii@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Auto-Submit: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1001906}

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

@@ -86,6 +86,7 @@
 #include "third_party/blink/renderer/core/layout/layout_object_factory.h"
 #include "third_party/blink/renderer/core/layout/layout_object_inl.h"
 #include "third_party/blink/renderer/core/layout/layout_object_inlines.h"
+#include "third_party/blink/renderer/core/layout/layout_ruby_run.h"
 #include "third_party/blink/renderer/core/layout/layout_table_caption.h"
 #include "third_party/blink/renderer/core/layout/layout_text_fragment.h"
 #include "third_party/blink/renderer/core/layout/layout_theme.h"
@@ -3760,6 +3761,12 @@ void LayoutObject::DestroyAndCleanupAnonymousWrappers(
     if (destroy_root_parent->Parent() &&
         destroy_root_parent->Parent()->IsLayoutNGFieldset())
       break;
+    // RubyBase should be kept if RubyText exists
+    if (destroy_root_parent->IsRubyBase()) {
+      auto* ruby_run = DynamicTo<LayoutRubyRun>(destroy_root_parent->Parent());
+      if (ruby_run && ruby_run->HasRubyText())
+        break;
+    }
 
     // We need to keep the anonymous parent, if it won't become empty by the
     // removal of this LayoutObject.

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

@@ -96,6 +96,7 @@ void LayoutRubyAsInline::AddChild(LayoutObject* child,
   if (!last_run || last_run->HasRubyText()) {
     last_run = LayoutRubyRun::StaticCreateRubyRun(this, *ContainingBlock());
     LayoutInline::AddChild(last_run, before_child);
+    last_run->RubyBaseSafe();
   }
   last_run->AddChild(child);
 }
@@ -164,6 +165,7 @@ void LayoutRubyAsBlock::AddChild(LayoutObject* child,
   if (!last_run || last_run->HasRubyText()) {
     last_run = LayoutRubyRun::StaticCreateRubyRun(this, *this);
     LayoutBlockFlow::AddChild(last_run, before_child);
+    last_run->RubyBaseSafe();
   }
   last_run->AddChild(child);
 }

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

@@ -46,9 +46,9 @@ namespace blink {
 //          0 or 1 LayoutRubyText - shuffled to the front in order to re-use
 //                                  existing block layouting
 //              0-n inline object(s)
-//          0 or 1 LayoutRubyBase - contains the inline objects that make up the
-//                                  ruby base
-//              1-n inline object(s)
+//          1 LayoutRubyBase - contains the inline objects that make up the
+//                             ruby base
+//              0-n inline object(s)
 //
 // Note: <rp> elements are defined as having 'display:none' and thus normally
 // are not assigned a layoutObject.

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

@@ -114,22 +114,24 @@ void LayoutRubyRun::AddChild(LayoutObject* child, LayoutObject* before_child) {
       DCHECK_EQ(before_child->Parent(), this);
       LayoutObject* ruby = Parent();
       DCHECK(ruby->IsRuby());
-      LayoutBlock* new_run = StaticCreateRubyRun(ruby, *ContainingBlock());
+      auto* new_run = StaticCreateRubyRun(ruby, *ContainingBlock());
       ruby->AddChild(new_run, NextSibling());
+      new_run->RubyBaseSafe();
       // Add the new ruby text and move the old one to the new run
       // Note: Doing it in this order and not using LayoutRubyRun's methods,
       // in order to avoid automatic removal of the ruby run in case there is no
       // other child besides the old ruby text.
       LayoutBlockFlow::AddChild(child, before_child);
       LayoutBlockFlow::RemoveChild(before_child);
       new_run->AddChild(before_child);
-    } else if (HasRubyBase()) {
+    } else if (RubyBase()->FirstChild()) {
       // Insertion before a ruby base object.
       // In this case we need insert a new run before the current one and split
       // the base.
       LayoutObject* ruby = Parent();
       LayoutRubyRun* new_run = StaticCreateRubyRun(ruby, *ContainingBlock());
       ruby->AddChild(new_run, this);
+      new_run->RubyBaseSafe();
       new_run->AddChild(child);
 
       // Make sure we don't leave anything in the percentage descendant
@@ -158,16 +160,14 @@ void LayoutRubyRun::RemoveChild(LayoutObject* child) {
   if (!BeingDestroyed() && !DocumentBeingDestroyed() && child->IsRubyText()) {
     LayoutRubyBase* base = RubyBase();
     LayoutObject* right_neighbour = NextSibling();
-    if (base && right_neighbour && right_neighbour->IsRubyRun()) {
-      // Ruby run without a base can happen only at the first run.
+    if (base->FirstChild() && right_neighbour && right_neighbour->IsRubyRun()) {
       auto* right_run = To<LayoutRubyRun>(right_neighbour);
-      if (right_run->HasRubyBase()) {
-        LayoutRubyBase* right_base = right_run->RubyBaseSafe();
+      LayoutRubyBase* right_base = right_run->RubyBaseSafe();
+      if (right_base->FirstChild()) {
         // Collect all children in a single base, then swap the bases.
         right_base->MoveChildren(base);
         MoveChildTo(right_run, base);
         right_run->MoveChildTo(this, right_base);
-        // The now empty ruby base will be removed below.
         DCHECK(!RubyBase()->FirstChild());
       }
     }
@@ -176,16 +176,12 @@ void LayoutRubyRun::RemoveChild(LayoutObject* child) {
   LayoutBlockFlow::RemoveChild(child);
 
   if (!BeingDestroyed() && !DocumentBeingDestroyed()) {
-    // Check if our base (if any) is now empty. If so, destroy it.
+    // If this has only an empty LayoutRubyBase, destroy this sub-tree.
     LayoutBlockFlow* base = RubyBase();
-    if (base && !base->FirstChild()) {
+    if (!HasRubyText() && !base->FirstChild()) {
       LayoutBlockFlow::RemoveChild(base);
       base->DeleteLineBoxTree();
       base->Destroy();
-    }
-
-    // If any of the above leaves the run empty, destroy it as well.
-    if (!HasRubyText() && !HasRubyBase()) {
       DeleteLineBoxTree();
       Destroy();
     }
@@ -200,6 +196,7 @@ LayoutRubyBase* LayoutRubyRun::CreateRubyBase() const {
       GetDocument().GetStyleResolver().CreateAnonymousStyleWithDisplay(
           StyleRef(), EDisplay::kBlock);
   new_style->SetTextAlign(ETextAlign::kCenter);  // FIXME: use WEBKIT_CENTER?
+  new_style->SetHasLineIfEmpty(true);
   layout_object->SetStyle(std::move(new_style));
   return layout_object;
 }

third_party/blink/web_tests/FlagExpectations/disable-layout-ng

@@ -621,6 +621,8 @@ crbug.com/1035708 virtual/css-highlight-inheritance/external/wpt/css/css-pseudo/
 crbug.com/1035708 virtual/css-highlight-inheritance/external/wpt/css/css-pseudo/selection-originating-decoration-color.html [ Failure ]
 
 ### external/wpt/css/css-ruby/
+crbug.com/591099 external/wpt/css/css-ruby/abs-in-ruby-base-container.html [ Failure ]
+crbug.com/591099 external/wpt/css/css-ruby/abs-in-ruby-base.html [ Failure ]
 crbug.com/591099 external/wpt/css/css-ruby/br-clear-all-002.html [ Failure ]
 crbug.com/591099 external/wpt/css/css-ruby/ruby-line-breaking-002.html [ Failure ]
 crbug.com/591099 external/wpt/css/css-ruby/ruby-with-floats-002.html [ Failure ]

third_party/blink/web_tests/TestExpectations

@@ -1183,8 +1183,6 @@ crbug.com/1238243 external/wpt/css/css-tables/collapsed-scroll-overflow.html [ F
 
 crbug.com/880802 external/wpt/css/css-contain/contain-layout-017.html [ Failure ]
 crbug.com/868704 external/wpt/css/css-contain/contain-layout-breaks-002.html [ Failure ]
-crbug.com/847274 external/wpt/css/css-contain/contain-paint-005.html [ Failure ]
-crbug.com/847274 external/wpt/css/css-contain/contain-paint-006.html [ Failure ]
 crbug.com/880802 external/wpt/css/css-contain/contain-paint-021.html [ Failure ]
 crbug.com/882367 external/wpt/css/css-contain/contain-paint-clip-015.html [ Failure ]
 crbug.com/882367 external/wpt/css/css-contain/contain-paint-clip-016.html [ Failure ]
@@ -2993,8 +2991,6 @@ crbug.com/1110401 external/wpt/css/css-pseudo/active-selection-045.html [ Failur
 crbug.com/1024156 external/wpt/css/css-pseudo/active-selection-027.html [ Failure ]
 crbug.com/1024156 external/wpt/css/css-pseudo/active-selection-025.html [ Failure ]
 
-crbug.com/27659 external/wpt/css/css-ruby/abs-in-ruby-base-container.html [ Failure ]
-crbug.com/27659 external/wpt/css/css-ruby/abs-in-ruby-base.html [ Failure ]
 crbug.com/27659 external/wpt/css/css-ruby/block-ruby-001.html [ Failure ]
 crbug.com/27659 external/wpt/css/css-ruby/block-ruby-002.html [ Failure ]
 crbug.com/27659 external/wpt/css/css-ruby/block-ruby-005.html [ Failure ]
@@ -3012,6 +3008,7 @@ crbug.com/27659 external/wpt/css/css-ruby/ruby-align-002a.html [ Failure ]
 crbug.com/27659 external/wpt/css/css-ruby/ruby-annotation-pairing-001.html [ Failure ]
 crbug.com/27659 external/wpt/css/css-ruby/ruby-base-container-abs.html [ Failure ]
 crbug.com/27659 external/wpt/css/css-ruby/ruby-base-container-float.html [ Failure ]
+crbug.com/27659 external/wpt/css/css-ruby/ruby-base-different-size.html [ Failure ]
 crbug.com/27659 external/wpt/css/css-ruby/ruby-bidi-002.html [ Failure ]
 crbug.com/27659 external/wpt/css/css-ruby/ruby-bidi-003.html [ Failure ]
 crbug.com/27659 external/wpt/css/css-ruby/ruby-box-generation-001.html [ Failure ]