Make LayoutState always be RAII

Source/core/rendering/RenderView.cpp

Index: Source/core/rendering/RenderView.cpp
diff --git a/Source/core/rendering/RenderView.cpp b/Source/core/rendering/RenderView.cpp
index bbb9ce50e38269377d5167f7072fd73250449716..121f41e4e1052eca31cfe5dc67efc614ffd2f62b 100644
--- a/Source/core/rendering/RenderView.cpp
+++ b/Source/core/rendering/RenderView.cpp
@@ -162,7 +162,7 @@ void RenderView::positionDialogs()
     }
 }
 
-void RenderView::layoutContent(const LayoutState& state)
+void RenderView::layoutContent()
 {
     ASSERT(needsLayout());
 
@@ -173,27 +173,27 @@ void RenderView::layoutContent(const LayoutState& state)
         positionDialogs();
 
 #ifndef NDEBUG
-    checkLayoutState(state);
+    checkLayoutState();
 #endif
 }
 
 #ifndef NDEBUG
-void RenderView::checkLayoutState(const LayoutState& state)
+void RenderView::checkLayoutState()
 {
     if (!RuntimeEnabledFeatures::repaintAfterLayoutEnabled()) {
         ASSERT(layoutDeltaMatches(LayoutSize()));
     }
     ASSERT(!m_layoutStateDisableCount);
-    ASSERT(m_layoutState == &state);
+    ASSERT(!m_layoutState->m_next);
 }
 #endif
 
-void RenderView::initializeLayoutState(LayoutState& state)
+void RootLayoutStateScope::initializeLayoutState()
 {
-    state.m_clipped = false;
-    state.m_pageLogicalHeight = m_pageLogicalHeight;
-    state.m_pageLogicalHeightChanged = m_pageLogicalHeightChanged;
-    state.m_isPaginated = state.m_pageLogicalHeight;
+    m_rootLayoutState.m_clipped = false;
+    m_rootLayoutState.m_pageLogicalHeight = m_view.m_pageLogicalHeight;
+    m_rootLayoutState.m_pageLogicalHeightChanged = m_view.m_pageLogicalHeightChanged;
+    m_rootLayoutState.m_isPaginated = m_rootLayoutState.m_pageLogicalHeight;
 }
 
 void RenderView::layout()
@@ -229,18 +229,15 @@ void RenderView::layout()
     if (!needsLayout())
         return;
 
-    LayoutState state;
-    initializeLayoutState(state);
+    RootLayoutStateScope rootLayoutStateScope(*this);
 
     m_pageLogicalHeightChanged = false;
-    m_layoutState = &state;
 
-    layoutContent(state);
+    layoutContent();
 
 #ifndef NDEBUG
-    checkLayoutState(state);
+    checkLayoutState();
 #endif
-    m_layoutState = 0;
     clearNeedsLayout();
 }