[LayoutNG] Move PrepareLayout to NGBlockNode::FirstChild

This isn't ideal, but it does make things faster.

A few more tests pass (don't timeout) only 1-2 additional failure.
So a net win?

Bug: 635619
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng
Change-Id: Id95bdd4ebcfd2534dbbf07b50a730c9961349713
Reviewed-on: https://chromium-review.googlesource.com/726846
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#510224}

third_party/WebKit/LayoutTests/FlagExpectations/enable-blink-features=LayoutNG

@@ -4009,7 +4009,7 @@ crbug.com/591099 fast/css/invalidation-errors-3.html [ Failure ]
 crbug.com/591099 fast/css/invalidation-errors.html [ Failure ]
 crbug.com/591099 fast/css/invalidation/fieldset-disabled.html [ Failure ]
 crbug.com/591099 fast/css/invalidation/valid-invalid-pseudo.html [ Failure ]
-crbug.com/591099 fast/css/large-numbers.html [ Failure Timeout ]
+crbug.com/591099 fast/css/large-numbers.html [ Crash Failure ]
 crbug.com/591099 fast/css/last-child-pseudo-class.html [ Failure ]
 crbug.com/591099 fast/css/last-child-style-sharing.html [ Failure ]
 crbug.com/591099 fast/css/last-of-type-pseudo-class.html [ Failure ]

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

@@ -542,10 +542,6 @@ void NGInlineNode::ShapeTextForFirstLineIfNeeded() {
 RefPtr<NGLayoutResult> NGInlineNode::Layout(
     const NGConstraintSpace& constraint_space,
     NGBreakToken* break_token) {
-  // TODO(kojii): Invalidate PrepareLayout() more efficiently.
-  InvalidatePrepareLayout();
-  PrepareLayout();
-
   NGInlineLayoutAlgorithm algorithm(*this, constraint_space,
                                     ToNGInlineBreakToken(break_token));
   RefPtr<NGLayoutResult> result = algorithm.Layout();
@@ -600,10 +596,6 @@ static LayoutUnit ComputeContentSize(NGInlineNode node,
 }
 
 MinMaxSize NGInlineNode::ComputeMinMaxSize() {
-  // TODO(kojii): Invalidate PrepareLayout() more efficiently.
-  InvalidatePrepareLayout();
-  PrepareLayout();
-
   // Run line breaking with 0 and indefinite available width.
 
   // TODO(kojii): There are several ways to make this more efficient and faster
@@ -628,9 +620,6 @@ MinMaxSize NGInlineNode::ComputeMinMaxSize() {
 }
 
 NGLayoutInputNode NGInlineNode::NextSibling() {
-  // TODO(kojii): Invalidate PrepareLayout() more efficiently.
-  InvalidatePrepareLayout();
-  PrepareLayout();
   return NGBlockNode(Data().next_sibling_);
 }
 

third_party/WebKit/Source/core/layout/ng/inline/ng_inline_node.h

@@ -55,6 +55,10 @@ class CORE_EXPORT NGInlineNode : public NGLayoutInputNode {
   // Instruct to re-compute |PrepareLayout| on the next layout.
   void InvalidatePrepareLayout();
 
+  // Prepare inline and text content for layout. Must be called before
+  // calling the Layout method.
+  void PrepareLayout();
+
   const String& Text() const { return Data().text_content_; }
   StringView Text(unsigned start_offset, unsigned end_offset) const {
     return StringView(Data().text_content_, start_offset,
@@ -83,9 +87,6 @@ class CORE_EXPORT NGInlineNode : public NGLayoutInputNode {
   String ToString() const;
 
  protected:
-  // Prepare inline and text content for layout. Must be called before
-  // calling the Layout method.
-  void PrepareLayout();
   bool IsPrepareLayoutFinished() const { return !Text().IsNull(); }
 
   void CollectInlines();

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

@@ -330,6 +330,7 @@ TEST_F(NGInlineNodeTest, MinMaxSize) {
   LoadAhem();
   SetupHtml("t", "<div id=t style='font:10px Ahem'>AB CDEF</div>");
   NGInlineNodeForTest node = CreateInlineNode();
+  node.PrepareLayout();
   MinMaxSize sizes = node.ComputeMinMaxSize();
   EXPECT_EQ(40, sizes.min_size);
   EXPECT_EQ(70, sizes.max_size);
@@ -339,6 +340,7 @@ TEST_F(NGInlineNodeTest, MinMaxSizeElementBoundary) {
   LoadAhem();
   SetupHtml("t", "<div id=t style='font:10px Ahem'>A B<span>C D</span></div>");
   NGInlineNodeForTest node = CreateInlineNode();
+  node.PrepareLayout();
   MinMaxSize sizes = node.ComputeMinMaxSize();
   // |min_content| should be the width of "BC" because there is an element
   // boundary between "B" and "C" but no break opportunities.

third_party/WebKit/Source/core/layout/ng/inline/ng_physical_text_fragment.h

@@ -109,7 +109,7 @@ class CORE_EXPORT NGPhysicalTextFragment final : public NGPhysicalFragment {
  private:
   // The text of NGInlineNode; i.e., of a parent block. The text for this
   // fragment is a substring(start_offset_, end_offset_) of this string.
-  const String& text_;
+  const String text_;
 
   // Deprecating, ItemIndexDeprecated().
   unsigned item_index_;

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

@@ -250,8 +250,13 @@ NGLayoutInputNode NGBlockNode::FirstChild() {
   auto* child = GetLayoutObjectForFirstChildNode(block);
   if (!child)
     return nullptr;
-  if (AreNGBlockFlowChildrenInline(block))
-    return NGInlineNode(block);
+  if (AreNGBlockFlowChildrenInline(block)) {
+    // TODO(kojii): Invalidate PrepareLayout() more efficiently.
+    NGInlineNode node(block);
+    node.InvalidatePrepareLayout();
+    node.PrepareLayout();
+    return node;
+  }
   return NGBlockNode(ToLayoutBox(child));
 }