Added CSSPropertyAPI and CSS padding properties which implement this API

third_party/WebKit/Source/core/css/properties/CSSPropertyDescriptor.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.
+
+#include "core/CSSPropertyNames.h"
+
+namespace blink {
+
+class CSSValue;
+class CSSParserTokenRange;
+class CSSParserContext;
+
+// Stores function pointers matching those declared in CSSPropertyAPI.
+struct CSSPropertyDescriptor {
+  const CSSValue* (*parseSingleValue)(CSSParserTokenRange&,
+                                      const CSSParserContext&);
+
+  // Stores whether or not this descriptor is for a valid property. Do not
+  // access the contents of this descriptor unless this value is true.
+  bool temporaryCanReadValue;

[alancutter (OOO until 2018), 2016/12/11 23:31:15]

TODO: Remove this once the switch in CSSPropertyParser::parseSingleValue() has
been completely replaced by CSSPropertyDescriptors.

[alancutter (OOO until 2018), 2016/12/11 23:37:04]

Alternate idea: Make get() return a const CSSPropertyDescriptor*.
Personally I'd do this but I'll leave the decision up to you.

[aazzam, 2016/12/12 03:37:32]

I've kept it as returning a reference rather than a pointer for performance. I
considered changing it to a pointer temporarily, rather than having a temporary
bool, but removing the bool temporaryCanReadValue is a simpler transition for
after we've implemented all the properties.

[Z_DONOTUSE, 2016/12/12 05:50:18]

I think Alan meant to add the TODO as a comment. Which, I agree with.

+
+  // Returns the corresponding CSSPropertyDescriptor for a given CSSPropertyID.
+  // Use this function to access the API for a property. Returns a descriptor
+  // with isValid set to false if no descriptor exists for this ID.
+  static const CSSPropertyDescriptor& get(CSSPropertyID);
+};
+
+}  // namespace blink