[layoutng] Correctly resolve indefinite percentages

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

Index: third_party/WebKit/Source/core/layout/ng/ng_length_utils.cc
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_length_utils.cc b/third_party/WebKit/Source/core/layout/ng/ng_length_utils.cc
index 53713be8297314022d3c48a35bd918882ad225a7..4b3c696319ee6505683707017a771e542303fc13 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_length_utils.cc
+++ b/third_party/WebKit/Source/core/layout/ng/ng_length_utils.cc
@@ -21,6 +21,7 @@ LayoutUnit resolveInlineLength(const NGConstraintSpace& constraintSpace,
                                LengthResolveType type) {
   // TODO(layout-ng): Handle min/max/fit-content
   DCHECK(!length.isMaxSizeNone());
+  DCHECK_NE(constraintSpace.ContainerSize().inlineSize, LayoutUnit(-1));

[eae, 2016/08/23 16:50:56]

Can the length ever go negative? If not change this check if it's is more than
or equal to zero.

If it can then we cannot use -1 as infinite and instead need to use
LayoutUnit::max

[cbiesinger, 2016/08/23 19:37:18]

Done. I don't think size can ever go negative.

 
   if (type == LengthResolveType::MinSize && length.isAuto())
     return LayoutUnit();
@@ -47,6 +48,12 @@ LayoutUnit resolveBlockLength(const NGConstraintSpace& constraintSpace,
   if (length.isMinContent() || length.isMaxContent() || length.isFitContent())
     return contentSize;
 
+  // Make sure that indefinite percentages resolve to -1, not to a random
+  // negative number.
+  if (length.hasPercent() &&
+      constraintSpace.ContainerSize().blockSize == LayoutUnit(-1))

[eae, 2016/08/23 16:50:57]

We might want to use a constant for infinite to improve readability/

[cbiesinger, 2016/08/23 19:37:18]

OK. Adding NGSizeIndefinite. Using a #define to avoid static initializers.

+    return contentSize;
+
   return valueForLength(length, constraintSpace.ContainerSize().blockSize);
 }
 
@@ -86,8 +93,12 @@ LayoutUnit computeBlockSizeForFragment(const NGConstraintSpace& constraintSpace,
   LayoutUnit extent =
       resolveBlockLength(constraintSpace, style.logicalHeight(), contentSize,
                          LengthResolveType::ContentSize);
-  Length maxLength = style.logicalMaxHeight();
+  if (extent == LayoutUnit(-1)) {
+    DCHECK_EQ(contentSize, LayoutUnit(-1));
+    return extent;
+  }
 
+  Length maxLength = style.logicalMaxHeight();
   if (!maxLength.isMaxSizeNone()) {
     LayoutUnit max = resolveBlockLength(constraintSpace, maxLength, contentSize,
                                         LengthResolveType::MaxSize);