[LayoutNG] Stretch content size of BFCs to encapsulate floats.

third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/ng/ng_block_layout_algorithm.h"
 
 #include "core/layout/ng/inline/ng_inline_node.h"
 #include "core/layout/ng/ng_absolute_utils.h"
 #include "core/layout/ng/ng_block_child_iterator.h"
 #include "core/layout/ng/ng_constraint_space.h"
@@ skipping 279 matching lines @@
   //   Bottom margins of an in-flow block box doesn't collapse with its last
   //   in-flow block-level child's bottom margin if the box has bottom
   //   border/padding.
   if (border_scrollbar_padding_.block_end ||
       ConstraintSpace().IsNewFormattingContext()) {
     content_size_ =
         std::max(content_size_, previous_inflow_position.logical_block_offset +
                                     end_margin_strut.Sum());
     end_margin_strut = NGMarginStrut();
   }
+
+  // If the current layout is a new formatting context, we need to encapsulate
+  // all of our floats.
+  if (ConstraintSpace().IsNewFormattingContext()) {
+    // We can use the BFC coordinates, as we are a new formatting context.
+    DCHECK_EQ(container_builder_.BfcOffset().value(), NGLogicalOffset());
+
+    WTF::Optional<LayoutUnit> float_end_offset =
+        GetClearanceOffset(ConstraintSpace().Exclusions(), EClear::kBoth);
+    if (float_end_offset)
+      content_size_ = std::max(content_size_, float_end_offset.value());
+  }
+
   content_size_ += border_scrollbar_padding_.block_end;
 
   // Recompute the block-axis size now that we know our content size.
   size.block_size =
       ComputeBlockSizeForFragment(ConstraintSpace(), Style(), content_size_);
   container_builder_.SetBlockSize(size.block_size);
 
   // Layout our absolute and fixed positioned children.
   NGOutOfFlowLayoutPart(ConstraintSpace(), Style(), &container_builder_).Run();
 
@@ skipping 402 matching lines @@
     if (is_new_fc) {
       space_available -= child_data.bfc_offset_estimate.block_offset;
     }
   }
   space_builder.SetFragmentainerSpaceAvailable(space_available);
 
   return space_builder.ToConstraintSpace(
       FromPlatformWritingMode(child_style.GetWritingMode()));
 }
 }  // namespace blink