[LayoutNG] Take overflow into account when column-balancing.

I didn't check why one test started to pass (it's not a very interesting
test for overflow).

Bug: 829028
Change-Id: I2c2d5fe3ea8c6a87f00df47f81d4158936d8a1bd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1742162Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#685349}

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

@@ -27,6 +27,37 @@ inline bool NeedsColumnBalancing(LayoutUnit block_size,
          style.GetColumnFill() == EColumnFill::kBalance;
 }
 
+LayoutUnit CalculateColumnContentBlockSize(
+    const NGPhysicalContainerFragment& fragment,
+    bool multicol_is_horizontal_writing_mode) {
+  // TODO(mstensho): Once LayoutNG is capable of calculating overflow on its
+  // own, we should probably just move over to relying on that machinery,
+  // instead of doing all this on our own.
+  LayoutUnit total_size;
+  for (const auto& child : fragment.Children()) {
+    LayoutUnit size;
+    LayoutUnit offset;
+    if (multicol_is_horizontal_writing_mode) {
+      offset = child.Offset().top;
+      size = child->Size().height;
+    } else {
+      offset = child.Offset().left;
+      size = child->Size().width;
+    }
+    if (child->IsContainer()) {
+      LayoutUnit children_size = CalculateColumnContentBlockSize(
+          To<NGPhysicalContainerFragment>(*child),
+          multicol_is_horizontal_writing_mode);
+      if (size < children_size)
+        size = children_size;
+    }
+    LayoutUnit block_end = offset + size;
+    if (total_size < block_end)
+      total_size = block_end;
+  }
+  return total_size;
+}
+
 }  // namespace
 
 NGColumnLayoutAlgorithm::NGColumnLayoutAlgorithm(
@@ -320,11 +351,9 @@ LayoutUnit NGColumnLayoutAlgorithm::CalculateBalancedColumnBlockSize(
       {Node(), fragment_geometry, space});
   scoped_refptr<const NGLayoutResult> result = balancing_algorithm.Layout();
 
-  // TODO(mstensho): This is where the fun begins. We need to examine the entire
-  // fragment tree, not just the root.
-  LayoutUnit single_strip_block_size =
-      NGFragment(space.GetWritingMode(), result->PhysicalFragment())
-          .BlockSize();
+  LayoutUnit single_strip_block_size = CalculateColumnContentBlockSize(
+      result->PhysicalFragment(),
+      IsHorizontalWritingMode(space.GetWritingMode()));
 
   // Some extra care is required the division here. We want a the resulting
   // LayoutUnit value to be large enough to prevent overflowing columns. Use

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

@@ -2430,6 +2430,41 @@ TEST_F(NGColumnLayoutAlgorithmTest, ColumnBalancingEmptyBlock) {
   EXPECT_EQ(expectation, dump);
 }
 
+TEST_F(NGColumnLayoutAlgorithmTest, ColumnBalancingOverflow) {
+  SetBodyInnerHTML(R"HTML(
+    <style>
+      #parent {
+        columns: 3;
+        column-gap: 10px;
+        width: 320px;
+      }
+    </style>
+    <div id="container">
+      <div id="parent">
+        <div style="width:30px; height:20px;">
+          <div style="width:33px; height:300px;"></div>
+        </div>
+      </div>
+    </div>
+  )HTML");
+
+  String dump = DumpFragmentTree(GetElementById("container"));
+  String expectation = R"DUMP(.:: LayoutNG Physical Fragment Tree ::.
+  offset:unplaced size:1000x100
+    offset:0,0 size:320x100
+      offset:0,0 size:100x20
+        offset:0,0 size:30x20
+          offset:0,0 size:33x100
+      offset:110,0 size:100x0
+        offset:0,0 size:30x0
+          offset:0,0 size:33x100
+      offset:220,0 size:100x0
+        offset:0,0 size:30x0
+          offset:0,0 size:33x100
+)DUMP";
+  EXPECT_EQ(expectation, dump);
+}
+
 TEST_F(NGColumnLayoutAlgorithmTest, ColumnBalancingLines) {
   SetBodyInnerHTML(R"HTML(
     <style>

third_party/blink/web_tests/TestExpectations

@@ -1370,7 +1370,6 @@ crbug.com/967329 virtual/layout_ng_experimental/external/wpt/css/css-multicol/co
 crbug.com/829028 virtual/layout_ng_experimental/external/wpt/css/css-multicol/filter-with-abspos.html [ Failure ]
 crbug.com/829028 virtual/layout_ng_experimental/external/wpt/css/css-multicol/float-and-block.html [ Failure ]
 crbug.com/829028 virtual/layout_ng_experimental/external/wpt/css/css-multicol/float-with-line-after-spanner.html [ Failure ]
-crbug.com/829028 virtual/layout_ng_experimental/external/wpt/css/css-multicol/going-out-of-flow-after-spanner.html [ Failure ]
 crbug.com/829028 virtual/layout_ng_experimental/external/wpt/css/css-multicol/inline-block-and-column-span-all.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_experimental/external/wpt/css/css-multicol/multicol-basic-001.html [ Failure ]
 crbug.com/591099 virtual/layout_ng_experimental/external/wpt/css/css-multicol/multicol-basic-002.html [ Failure ]