[layoutng] Add a function to compute the min- and max-content contribution

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

Index: third_party/WebKit/Source/core/layout/ng/ng_length_utils.h
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_length_utils.h b/third_party/WebKit/Source/core/layout/ng/ng_length_utils.h
index 6d5eb70227e7762e0341bf10659fbe31b3faae52..9e67b620f09f9607457d2873379ce274d4a1daee 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_length_utils.h
+++ b/third_party/WebKit/Source/core/layout/ng/ng_length_utils.h
@@ -35,6 +35,11 @@ enum class LengthResolveType {
 // MinAndMaxContentSizes struct to those functions.
 CORE_EXPORT bool NeedMinAndMaxContentSizes(const ComputedStyle&);
 
+// Like NeedMinAndMaxContentSizes, but for use when calling
+// ComputeMinAndMaxContentContribution.
+CORE_EXPORT bool NeedMinAndMaxContentSizesForContentContribution(
+    const ComputedStyle&);
+
 // Convert an inline-axis length to a layout unit using the given constraint
 // space.
 CORE_EXPORT LayoutUnit
@@ -52,6 +57,17 @@ CORE_EXPORT LayoutUnit ResolveBlockLength(const NGConstraintSpace&,
                                           LayoutUnit content_size,
                                           LengthResolveType);
 
+// For the given style and min/max content sizes, computes the min and max
+// content contribution (https://drafts.csswg.org/css-sizing/#contributions).
+// This is similar to ComputeInlineSizeForFragment except that it does not
+// require a constraint space (percentage sizes as well as auto margins compute
+// to zero) and that an auto inline size resolves to the respective min/max
+// content size.
+// Also, the min/max contribution does include the inline margins as well.
+CORE_EXPORT MinAndMaxContentSizes ComputeMinAndMaxContentContribution(
+    const ComputedStyle&,
+    const WTF::Optional<MinAndMaxContentSizes>&);
+
 // Resolves the given length to a layout unit, constraining it by the min
 // logical width and max logical width properties from the ComputedStyle
 // object.