Make room for any scrollbars in the content box and border box.

third_party/WebKit/Source/core/layout/LayoutBox.cpp

Index: third_party/WebKit/Source/core/layout/LayoutBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBox.cpp b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
index a35862c461793a1fd504d8c8cc86ad5e55166bba..092d313fa65dba5601ce612c348baed1818f57ad 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
@@ -984,17 +984,6 @@ int LayoutBox::HorizontalScrollbarHeight() const {
   return GetScrollableArea()->HorizontalScrollbarHeight();
 }
 
-LayoutUnit LayoutBox::VerticalScrollbarWidthClampedToContentBox() const {
-  LayoutUnit width(VerticalScrollbarWidth());
-  DCHECK_GE(width, LayoutUnit());
-  if (width) {
-    LayoutUnit minimum_width = LogicalWidth() - BorderAndPaddingLogicalWidth();
-    DCHECK_GE(minimum_width, LayoutUnit());
-    width = std::min(width, minimum_width);
-  }
-  return width;
-}
-
 ScrollResult LayoutBox::Scroll(ScrollGranularity granularity,
                                const FloatSize& delta) {
   // Presumably the same issue as in setScrollTop. See crbug.com/343132.
@@ -1470,19 +1459,21 @@ void LayoutBox::ClearOverrideContainingBlockContentLogicalHeight() {
 LayoutUnit LayoutBox::AdjustBorderBoxLogicalWidthForBoxSizing(
     float width) const {
   LayoutUnit borders_plus_padding = CollapsedBorderAndCSSPaddingLogicalWidth();
+  LayoutUnit scrollbar_size(VerticalScrollbarWidth());
   LayoutUnit result(width);
   if (Style()->BoxSizing() == EBoxSizing::kContentBox)
-    return result + borders_plus_padding;
-  return std::max(result, borders_plus_padding);
+    return std::max(result, scrollbar_size) + borders_plus_padding;
+  return std::max(result, borders_plus_padding + scrollbar_size);
 }
 
 LayoutUnit LayoutBox::AdjustBorderBoxLogicalHeightForBoxSizing(
     float height) const {
   LayoutUnit borders_plus_padding = CollapsedBorderAndCSSPaddingLogicalHeight();
+  LayoutUnit scrollbar_size(HorizontalScrollbarHeight());
   LayoutUnit result(height);
   if (Style()->BoxSizing() == EBoxSizing::kContentBox)
-    return result + borders_plus_padding;
-  return std::max(result, borders_plus_padding);
+    return std::max(result, scrollbar_size) + borders_plus_padding;
+  return std::max(result, borders_plus_padding + scrollbar_size);
 }
 
 LayoutUnit LayoutBox::AdjustContentBoxLogicalWidthForBoxSizing(
@@ -1490,7 +1481,7 @@ LayoutUnit LayoutBox::AdjustContentBoxLogicalWidthForBoxSizing(
   LayoutUnit result(width);
   if (Style()->BoxSizing() == EBoxSizing::kBorderBox)
     result -= CollapsedBorderAndCSSPaddingLogicalWidth();
-  return std::max(LayoutUnit(), result);
+  return std::max(LayoutUnit(VerticalScrollbarWidth()), result);
 }
 
 LayoutUnit LayoutBox::AdjustContentBoxLogicalHeightForBoxSizing(
@@ -1498,7 +1489,7 @@ LayoutUnit LayoutBox::AdjustContentBoxLogicalHeightForBoxSizing(
   LayoutUnit result(height);
   if (Style()->BoxSizing() == EBoxSizing::kBorderBox)
     result -= CollapsedBorderAndCSSPaddingLogicalHeight();
-  return std::max(LayoutUnit(), result);
+  return std::max(LayoutUnit(HorizontalScrollbarHeight()), result);
 }
 
 // Hit Testing