[CSS Typed OM] Make the attributes of CSSPerspective mutable.

third_party/WebKit/Source/core/css/cssom/CSSPerspective.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CSSPerspective_h
 #define CSSPerspective_h
 
 #include "core/CoreExport.h"
 #include "core/css/cssom/CSSNumericValue.h"
 #include "core/css/cssom/CSSTransformComponent.h"
 
 namespace blink {
 
 class DOMMatrix;
 class ExceptionState;
 
 // Represents a perspective value in a CSSTransformValue used for properties
 // like "transform".
 // See CSSPerspective.idl for more information about this class.
-class CORE_EXPORT CSSPerspective : public CSSTransformComponent {
+class CORE_EXPORT CSSPerspective final : public CSSTransformComponent {
   WTF_MAKE_NONCOPYABLE(CSSPerspective);
   DEFINE_WRAPPERTYPEINFO();
 
  public:
   // Constructor defined in the IDL.
   static CSSPerspective* Create(CSSNumericValue*, ExceptionState&);
 
   // Blink-internal ways of creating CSSPerspectives.
   static CSSPerspective* FromCSSValue(const CSSFunctionValue&);
 
   // Getters and setters for attributes defined in the IDL.
-  // Bindings require a non const return value.

[alancutter (OOO until 2018), 2017/06/19 04:27:18]

I think this comment is useful, I'd be in favour of keeping it to explain the
weird constness here.
I'd even consider making these getters non-const if it's not needed for
anything.

[meade_UTC10, 2017/06/19 08:07:40]

I removed the comment because we no longer need the const_cast, which is what it
was referring to?

[alancutter (OOO until 2018), 2017/06/19 10:55:11]

It's the fact that it's returning non-const member pointers from const getters
that's worth justifying with a comment.
https://www.chromium.org/developers/coding-style/cpp-dos-and-donts#TOC-Use-co...

-  CSSNumericValue* length() const {
-    return const_cast<CSSNumericValue*>(length_.Get());
-  }
+  CSSNumericValue* length() const { return length_.Get(); }
+  void setLength(CSSNumericValue*, ExceptionState&);
 
   // Internal methods - from CSSTransformComponent.
-  TransformComponentType GetType() const override { return kPerspectiveType; }
+  TransformComponentType GetType() const final { return kPerspectiveType; }
   // TODO: Implement AsMatrix for CSSPerspective.
-  DOMMatrix* AsMatrix() const override { return nullptr; }
-  CSSFunctionValue* ToCSSValue() const override;
+  DOMMatrix* AsMatrix() const final { return nullptr; }
+  CSSFunctionValue* ToCSSValue() const final;
 
   DEFINE_INLINE_VIRTUAL_TRACE() {
     visitor->Trace(length_);
     CSSTransformComponent::Trace(visitor);
   }
 
  private:
-  CSSPerspective(const CSSNumericValue* length) : length_(length) {}
+  CSSPerspective(CSSNumericValue* length) : length_(length) {}
 
-  Member<const CSSNumericValue> length_;
+  Member<CSSNumericValue> length_;
 };
 
 }  // namespace blink
 
 #endif