Added CSSPropertyAPI and CSS padding properties which implement this API

third_party/WebKit/Source/core/css/properties/CSSPropertyDescriptor.cpp

+// 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/css/properties/CSSPropertyDescriptor.h"
+
+#include "core/css/properties/CSSPropertyAPIPadding.h"
+
+namespace blink {
+
+// Initialises a CSSPropertyDescriptor. When functions are added to
+// CSSPropertyAPI, also add them to the struct initaliser below.
+#define GET_DESCRIPTOR(X) \
+  { X::parseSingleValue, true }
+
+// Initialises an invalid CSSPropertyDescriptor. When functions are added to
+// CSSPropertyAPI, add a nullptr to represent their function pointers in the
+// struct initaliser.
+#define GET_INVALID_DESCRIPTOR() \
+  { nullptr, false }
+
+static_assert(
+    std::is_pod<CSSPropertyDescriptor>::value,
+    "CSSPropertyDescriptor must be a POD to support using initializer lists.");
+
+static CSSPropertyDescriptor cssPropertyDescriptors[] = {
+    GET_INVALID_DESCRIPTOR(), GET_DESCRIPTOR(CSSPropertyAPIWebkitPadding),
+};
+
+const CSSPropertyDescriptor& CSSPropertyDescriptor::get(CSSPropertyID id) {
+  // TODO(aazzam): We are currently using hard-coded indexes for
+  // cssPropertyDescriptor since we have only implemented a few properties.
+  // Later, generate this switch statement, or alternatively return
+  // cssPropertyDescriptors[id], and generate the cssPropertyDescriptors array
+  // to hold invalid descriptors for methods which haven't been implemented yet.
+  switch (id) {
+    case CSSPropertyWebkitPaddingEnd:
+      return cssPropertyDescriptors[1];
+    case CSSPropertyWebkitPaddingStart:
+      return cssPropertyDescriptors[1];
+    case CSSPropertyWebkitPaddingBefore:
+      return cssPropertyDescriptors[1];
+    case CSSPropertyWebkitPaddingAfter:
+      return cssPropertyDescriptors[1];
+    default:
+      return cssPropertyDescriptors[0];
+  }
+}
+
+}  // namespace blink