[LayoutNG] Fix inline out-of-flow container computation

The out-of-flow code assumed that all fragments for a
LayoutInline has the same height, but the change for
crbug.com/903578 (WIP CL:1251142) breaks the assumption.

This patch fixes by computing the rect and uniting them,
instead of taking the max of heights.

No behavior changes until the WIP CL lands.

Change-Id: I9fe6b35d25836fde10dd88dd90ca2a810f5c9863
Bug: 636993, 903578
Reviewed-on: https://chromium-review.googlesource.com/c/1351189Reviewed-by: Aleks Totic <atotic@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610994}

third_party/blink/renderer/core/layout/ng/ng_box_fragment_builder.cc

@@ -219,6 +219,10 @@ void NGBoxFragmentBuilder::ComputeInlineContainerFragments(
     if (children_[i]->IsLineBox()) {
       const NGPhysicalLineBoxFragment* linebox =
           ToNGPhysicalLineBoxFragment(children_[i].get());
+      const NGPhysicalOffset linebox_offset = offsets_[i].ConvertToPhysical(
+          GetWritingMode(), Direction(),
+          ToNGPhysicalSize(Size(), GetWritingMode()), linebox->Size());
+
       for (auto& descendant :
            NGInlineFragmentTraversal::DescendantsOf(*linebox)) {
         LayoutObject* key = {};
@@ -230,54 +234,31 @@ void NGBoxFragmentBuilder::ComputeInlineContainerFragments(
         } else if (descendant.fragment->IsBox()) {
           key = descendant.fragment->GetLayoutObject();
         }
-        if (key && inline_container_fragments->Contains(key)) {
-          NGBoxFragmentBuilder::FragmentPair value =
-              inline_container_fragments->at(key);
-          if (!value.start_fragment) {
+        if (!key)
+          continue;
+        auto it = inline_container_fragments->find(key);
+        if (it != inline_container_fragments->end()) {
+          NGBoxFragmentBuilder::FragmentPair& value = it->value;
+          // |DescendantsOf| returns the offset from the given fragment. Since
+          // we give it the line box, need to add the |linebox_offset|.
+          NGPhysicalOffsetRect fragment_rect(
+              linebox_offset + descendant.offset_to_container_box,
+              descendant.fragment->Size());
+          if (value.start_linebox_fragment == linebox) {
+            value.start_fragment_union_rect.Unite(fragment_rect);
+          } else if (!value.start_fragment) {
             value.start_fragment = descendant.fragment.get();
-            value.start_fragment_union_rect.offset =
-                descendant.offset_to_container_box;
-            value.start_fragment_union_rect =
-                NGPhysicalOffsetRect(descendant.offset_to_container_box,
-                                     value.start_fragment->Size());
+            value.start_fragment_union_rect = fragment_rect;
             value.start_linebox_fragment = linebox;
-            value.start_linebox_offset = offsets_.at(i);
           }
-          if (!value.end_fragment || value.end_linebox_fragment != linebox) {
+          // Skip fragments within an empty line boxes for the end fragment.
+          if (value.end_linebox_fragment == linebox) {
+            value.end_fragment_union_rect.Unite(fragment_rect);
+          } else if (!value.end_fragment || !linebox->IsEmptyLineBox()) {
             value.end_fragment = descendant.fragment.get();
-            value.end_fragment_union_rect = NGPhysicalOffsetRect(
-                descendant.offset_to_container_box, value.end_fragment->Size());
+            value.end_fragment_union_rect = fragment_rect;
             value.end_linebox_fragment = linebox;
-            value.end_linebox_offset = offsets_.at(i);
-          }
-          // Extend the union size
-          if (value.start_linebox_fragment == linebox) {
-            // std::max because initial box might have larger extent than its
-            // descendants.
-            value.start_fragment_union_rect.size.width =
-                std::max(descendant.offset_to_container_box.left +
-                             descendant.fragment->Size().width -
-                             value.start_fragment_union_rect.offset.left,
-                         value.start_fragment_union_rect.size.width);
-            value.start_fragment_union_rect.size.height =
-                std::max(descendant.offset_to_container_box.top +
-                             descendant.fragment->Size().height -
-                             value.start_fragment_union_rect.offset.top,
-                         value.start_fragment_union_rect.size.height);
-          }
-          if (value.end_linebox_fragment == linebox) {
-            value.end_fragment_union_rect.size.width =
-                std::max(descendant.offset_to_container_box.left +
-                             descendant.fragment->Size().width -
-                             value.start_fragment_union_rect.offset.left,
-                         value.end_fragment_union_rect.size.width);
-            value.end_fragment_union_rect.size.height =
-                std::max(descendant.offset_to_container_box.top +
-                             descendant.fragment->Size().height -
-                             value.start_fragment_union_rect.offset.top,
-                         value.end_fragment_union_rect.size.height);
           }
-          inline_container_fragments->Set(key, value);
         }
       }
     }

third_party/blink/renderer/core/layout/ng/ng_box_fragment_builder.h

@@ -213,8 +213,6 @@ class CORE_EXPORT NGBoxFragmentBuilder final
     DISALLOW_NEW();
     // Linebox that contains start_fragment.
     const NGPhysicalLineBoxFragment* start_linebox_fragment;
-    // Offset of start_linebox from containing block.
-    NGLogicalOffset start_linebox_offset;
     // Start fragment of inline containing block.
     const NGPhysicalFragment* start_fragment;
     // Start fragment rect combined with rectangles of all fragments
@@ -222,7 +220,6 @@ class CORE_EXPORT NGBoxFragmentBuilder final
     NGPhysicalOffsetRect start_fragment_union_rect;
     // end_** variables are end fragment counterparts to start fragment.
     const NGPhysicalLineBoxFragment* end_linebox_fragment;
-    NGLogicalOffset end_linebox_offset;
     const NGPhysicalFragment* end_fragment;
     NGPhysicalOffsetRect end_fragment_union_rect;
   };

third_party/blink/renderer/core/layout/ng/ng_out_of_flow_layout_part.cc

@@ -199,11 +199,6 @@ void NGOutOfFlowLayoutPart::ComputeInlineContainingBlocks(
           start_fragment_logical_offset.ConvertToPhysical(
               container_writing_mode, container_direction,
               start_linebox_fragment->Size(), NGPhysicalSize());
-      NGPhysicalOffset start_linebox_physical_offset =
-          block_info.value.start_linebox_offset.ConvertToPhysical(
-              container_writing_mode, container_direction,
-              container_builder_physical_size, start_linebox_fragment->Size());
-      start_fragment_physical_offset += start_linebox_physical_offset;
       // Step 2
       const NGPhysicalLineBoxFragment* end_linebox_fragment =
           block_info.value.end_linebox_fragment;
@@ -228,11 +223,6 @@ void NGOutOfFlowLayoutPart::ComputeInlineContainingBlocks(
           end_fragment_bottom_right.ConvertToPhysical(
               container_writing_mode, container_direction,
               end_linebox_fragment->Size(), NGPhysicalSize());
-      NGPhysicalOffset end_linebox_physical_offset =
-          block_info.value.end_linebox_offset.ConvertToPhysical(
-              container_writing_mode, container_direction,
-              container_builder_physical_size, end_linebox_fragment->Size());
-      end_fragment_physical_offset += end_linebox_physical_offset;
       // Step 3
       NGLogicalOffset start_fragment_logical_offset_wrt_box =
           start_fragment_physical_offset.ConvertToLogical(