[layout-ng] Convert ng_block_layout_algorithm to yield to the coordinator

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

Index: third_party/WebKit/Source/core/layout/ng/ng_layout_coordinator.cc
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_layout_coordinator.cc b/third_party/WebKit/Source/core/layout/ng/ng_layout_coordinator.cc
index 15adc8a817a2b6298cf841a5af9aee4f68fc6f68..3876200b6611f0e48b91e4b2b8121a4a1fe1a201 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_layout_coordinator.cc
+++ b/third_party/WebKit/Source/core/layout/ng/ng_layout_coordinator.cc
@@ -5,6 +5,7 @@
 #include "core/layout/ng/ng_layout_coordinator.h"
 
 #include "core/layout/ng/ng_layout_input_node.h"
+#include "core/layout/ng/ng_physical_fragment_base.h"
 
 namespace blink {
 
@@ -15,20 +16,28 @@ NGLayoutCoordinator::NGLayoutCoordinator(
       NGLayoutInputNode::AlgorithmForInputNode(input_node, constraint_space));
 }
 
-bool NGLayoutCoordinator::Tick(NGPhysicalFragmentBase** fragment) {
+bool NGLayoutCoordinator::Tick(NGPhysicalFragmentBase** out_fragment) {
   NGLayoutAlgorithm* child_algorithm;
 
   // Tick should never be called without a layout algorithm on the stack.
   DCHECK(layout_algorithms_.size());
 
-  // TODO(layout-dev): store box from last tick and pass it into Layout here.
-  switch (
-      layout_algorithms_.back()->Layout(nullptr, fragment, &child_algorithm)) {
+  NGPhysicalFragmentBase* fragment;
+  NGPhysicalFragmentBase* in_fragment = fragment_;
+  fragment_ = nullptr;
+
+  switch (layout_algorithms_.back()->Layout(in_fragment, &fragment,
+                                            &child_algorithm)) {
     case kNotFinished:
       return false;
     case kNewFragment:
       layout_algorithms_.pop_back();
-      return (layout_algorithms_.size() == 0);
+      if (layout_algorithms_.size() == 0) {
+        *out_fragment = fragment;
+        return true;
+      }
+      fragment_ = fragment;
+      return false;
     case kChildAlgorithmRequired:
       layout_algorithms_.append(child_algorithm);
       return false;
@@ -40,5 +49,6 @@ bool NGLayoutCoordinator::Tick(NGPhysicalFragmentBase** fragment) {
 
 DEFINE_TRACE(NGLayoutCoordinator) {
   visitor->trace(layout_algorithms_);
+  visitor->trace(fragment_);
 }
 }