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.
+  // TODO(aazzam): Remove this once the switch in
+  // CSSPropertyParser::parseSingleValue() has been completely replaced by
+  // CSSPropertyDescriptors.
+  bool temporaryCanReadValue;
+
+  // 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