[LayoutNG] Compute baseline from fragment tree

third_party/WebKit/Source/core/layout/ng/inline/ng_baseline.cc

Index: third_party/WebKit/Source/core/layout/ng/inline/ng_baseline.cc
diff --git a/third_party/WebKit/Source/core/layout/ng/inline/ng_baseline.cc b/third_party/WebKit/Source/core/layout/ng/inline/ng_baseline.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b85f3730897b5cdfc28924ab5d0868b5bd0d5b52
--- /dev/null
+++ b/third_party/WebKit/Source/core/layout/ng/inline/ng_baseline.cc
@@ -0,0 +1,42 @@
+// Copyright 2017 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/inline/ng_baseline.h"
+
+#include "core/layout/LayoutBlock.h"
+#include "core/layout/ng/ng_block_node.h"
+#include "core/layout/ng/ng_layout_input_node.h"
+
+namespace blink {
+
+bool NGBaseline::ShouldPropagateBaselines(const NGLayoutInputNode node) {
+  if (node.IsInline())
+    return true;
+
+  return ShouldPropagateBaselines(ToLayoutBox(node.GetLayoutObject()));
+}
+
+bool NGBaseline::ShouldPropagateBaselines(LayoutBox* layout_box) {
+  // Test if this node should use its own box to synthesize the baseline.
+  if (!layout_box->IsLayoutBlock() ||
+      layout_box->IsFloatingOrOutOfFlowPositioned() ||
+      layout_box->IsWritingModeRoot())
+    return false;
+
+  // If this node is LayoutBlock that uses old layout, this may be a subclass
+  // that overrides baseline functions. Propagate baseline requests so that we
+  // call virtual functions.
+  if (!NGBlockNode(layout_box).CanUseNewLayout())
+    return true;
+
+  // CSS defines certain cases to synthesize baselines from box. See comments in
+  // UseLogicalBottomMarginEdgeForInlineBlockBaseline().
+  const LayoutBlock* layout_block = ToLayoutBlock(layout_box);
+  if (layout_block->UseLogicalBottomMarginEdgeForInlineBlockBaseline())
+    return false;
+
+  return true;
+}
+
+}  // namespace blink