Add grid/flex layout support for <fieldset>

third_party/WebKit/Source/core/layout/LayoutFieldset.h

Index: third_party/WebKit/Source/core/layout/LayoutFieldset.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutFieldset.h b/third_party/WebKit/Source/core/layout/LayoutFieldset.h
index d00d1682b7c977566c55d222bfbdd43a87b69232..843c8413707d5946b93fc4ccf7bb3ead9be883db 100644
--- a/third_party/WebKit/Source/core/layout/LayoutFieldset.h
+++ b/third_party/WebKit/Source/core/layout/LayoutFieldset.h
@@ -24,11 +24,11 @@
 #ifndef LayoutFieldset_h
 #define LayoutFieldset_h
 
-#include "core/layout/LayoutBlockFlow.h"
+#include "core/layout/LayoutFlexibleBox.h"
 
 namespace blink {
 
-class LayoutFieldset final : public LayoutBlockFlow {
+class LayoutFieldset final : public LayoutFlexibleBox {

[Manuel Rego, 2016/07/20 06:00:23]

Are we sure we want to do this change?
Inheriting from Flexbox might be a bad idea thinking on the long term.
What's the main reason to do this?

We've been getting rid of this kind of inheritance as they cause issues
when you're developing things on Flexbox.
Some changes on Flexbox might affect the classes inheriting for him,
so you might be broken things or you might need to tweak things in many places.
IMHO, we should try to avoid this kind of things as the code becomes
very complex.

For example, we're using Flexbox for full-screen and we want to avoid it,
and this was causing issues when implementing some alignment stuff.

[Gleb Lanbin, 2016/07/21 18:25:31]

please see the reply from cbiesenger@ on a similar question below.

 public:
     explicit LayoutFieldset(Element*);
 
@@ -37,15 +37,29 @@ public:
     const char* name() const override { return "LayoutFieldset"; }
 
 private:
-    bool isOfType(LayoutObjectType type) const override { return type == LayoutObjectFieldset || LayoutBlockFlow::isOfType(type); }
-
-    LayoutObject* layoutSpecialExcludedChild(bool relayoutChildren, SubtreeLayoutScope&) override;
-
-    void computePreferredLogicalWidths() override;
+    void addChild(LayoutObject* newChild, LayoutObject* beforeChild = nullptr) override;
     bool avoidsFloats() const override { return true; }
 
+    // Let the baseline to be the bottom of our margin box.
+    int baselinePosition(FontBaseline, bool firstLine, LineDirectionMode, LinePositionMode) const override;
+    int inlineBlockBaseline(LineDirectionMode) const override { return -1; }
+
+    void computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const override;
+    bool createsAnonymousWrapper() const override { return true; }
+    bool isOfType(LayoutObjectType type) const override { return type == LayoutObjectFieldset || LayoutFlexibleBox::isOfType(type); }
+    LayoutObject* layoutSpecialExcludedChild(bool relayoutChildren, SubtreeLayoutScope&) override;
     void paintBoxDecorationBackground(const PaintInfo&, const LayoutPoint&) const override;
     void paintMask(const PaintInfo&, const LayoutPoint&) const override;
+    void styleDidChange(StyleDifference, const ComputedStyle* oldStyle) override;
+    void updateLogicalWidth() override;
+
+    void adjustInnerStyle();
+    void createInnerBlock();
+    void setLogicalLeftForChild(LayoutBox& child, LayoutUnit logicalLeft);
+    void setLogicalTopForChild(LayoutBox& child, LayoutUnit logicalTop);
+    void removeChild(LayoutObject*) override;
+
+    LayoutBlock* m_innerBlock;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutFieldset, isFieldset());