[LayoutNG] Very simple layout() implementation

third_party/WebKit/Source/core/layout/ng/NGBlockLayoutAlgorithm.h

Index: third_party/WebKit/Source/core/layout/ng/NGBlockLayoutAlgorithm.h
diff --git a/third_party/WebKit/Source/core/layout/ng/NGBlockLayoutAlgorithm.h b/third_party/WebKit/Source/core/layout/ng/NGBlockLayoutAlgorithm.h
index 3f3645affdc1b1fde538c42e170eae7c0a547902..e250fc06f9808f82430cd2215b749355f736c8f0 100644
--- a/third_party/WebKit/Source/core/layout/ng/NGBlockLayoutAlgorithm.h
+++ b/third_party/WebKit/Source/core/layout/ng/NGBlockLayoutAlgorithm.h
@@ -5,11 +5,29 @@
 #ifndef NGBlockLayoutAlgorithm_h
 #define NGBlockLayoutAlgorithm_h
 
+#include "wtf/RefPtr.h"
+
 namespace blink {
 
+class ComputedStyle;
+class LayoutBox;
+class NGConstraintSpace;
+class NGFragment;
+
+// A class for general block layout (e.g. a <div> with no special style).
+// Lays out the children in sequence.
 class NGBlockLayoutAlgorithm {
 public:
-    NGBlockLayoutAlgorithm();
+    NGBlockLayoutAlgorithm(const ComputedStyle*);
+
+    // Actual layout implementation. Lays out the children in sequence within
+    // the constraints given by the NGConstraintSpace. Returns a fragment
+    // with the resulting layout information.
+    // This function can not be const because for interruptible layout, we have
+    // to be able to store state information.
+    NGFragment* layout(const NGConstraintSpace&);
+private:
+    RefPtr<const ComputedStyle> m_style;
 };
 
 } // namespace blink