From 79b640795aacac89e67043a22cb3ceb622bd0864 Mon Sep 17 00:00:00 2001
From: FranklinDM <mrmineshafter17@gmail.com>
Date: Wed, 6 Apr 2022 23:59:01 +0800
Subject: Issue #1370 - Part 3: Implement `content` keyword for `flex-basis`
 property

Partially based on https://bugzilla.mozilla.org/show_bug.cgi?id=1105111
---
 layout/generic/nsFrame.cpp | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

(limited to 'layout/generic/nsFrame.cpp')

diff --git a/layout/generic/nsFrame.cpp b/layout/generic/nsFrame.cpp
index 99442e681f..141c148673 100644
--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -4647,11 +4647,23 @@ nsFrame::SetCoordToFlexBasis(bool aIsInlineFlexItem,
     return;
   }
 
+  const nsStyleCoord* newCoord = aFlexBasis;
+
+  // Having 'content' as the value of the 'flex-basis' property is
+  // equivalent to setting both 'flex-basis' and the main size
+  // properties to 'auto', which is why a dummy 'auto' value will
+  // be used here for the main size property.
+  if (aFlexBasis->GetUnit() == eStyleUnit_Enumerated &&
+      aFlexBasis->GetIntValue() == NS_STYLE_FLEX_BASIS_CONTENT) {
+    static const nsStyleCoord autoStyleCoord(eStyleUnit_Auto);
+    newCoord = &autoStyleCoord;
+  }
+
   // Override whichever styleCoord is in the flex container's main axis
   if (aIsInlineFlexItem) {
-    *aInlineStyle = aFlexBasis;
+    *aInlineStyle = newCoord;
   } else {
-    *aBlockStyle = aFlexBasis;
+    *aBlockStyle = newCoord;
   }
 }
 
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