Added CSSPropertyAPI and CSS padding properties which implement this API

third_party/WebKit/Source/core/css/properties/CSSPropertyAPI.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 CSSPropertyAPI_h
+#define CSSPropertyAPI_h
+
+#include "core/CSSPropertyNames.h"
+#include "core/css/CSSValue.h"
+#include "core/css/parser/CSSParserMode.h"
+#include "core/css/parser/CSSParserTokenRange.h"
+
+namespace blink {
+
+/*
+An API for CSS properties which allows you to call functions on properties
+from within the parser. To enusre that all functions are implemented, provide
+implementations for all functions with a default implementation or
+NOTREACHED().
+*/
+class CSSPropertyAPI {
+ public:
+  // Parses the CSS property and returns a CSS Value.
+  static const CSSValue* parseSingleValue(CSSParserTokenRange&,
+                                          const CSSParserContext&) {
+    NOTREACHED();
+    return nullptr;
+  }
+
+  // Returns the CSSPropertyID of the property
+  static inline CSSPropertyID getID() {
+    NOTREACHED();
+    return CSSPropertyInvalid;
+  }
+};
+}
+
+#endif  // CSSPropertyAPI_h