Update the snap points css properties

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

+// Copyright 2017 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/CSSPropertyAPIScrollSnapAlign.h"
+
+#include "core/css/CSSValuePair.h"
+#include "core/css/parser/CSSPropertyParserHelpers.h"
+
+namespace blink {
+
+const CSSValue* CSSPropertyAPIScrollSnapAlign::parseSingleValue(
+    CSSParserTokenRange& range,
+    const CSSParserContext& context,
+    const CSSParserLocalContext&) {
+  CSSValueID x_id = range.Peek().Id();
+  if (x_id != CSSValueNone && x_id != CSSValueStart && x_id != CSSValueEnd &&
+      x_id != CSSValueCenter)
+    return nullptr;
+  CSSValue* x_value = CSSPropertyParserHelpers::ConsumeIdent(range);
+  if (range.AtEnd())
+    return x_value;
+
+  CSSValueID y_id = range.Peek().Id();
+  if (y_id != CSSValueNone && y_id != CSSValueStart && y_id != CSSValueEnd &&
+      y_id != CSSValueCenter)
+    return x_value;
+  CSSValue* y_value = CSSPropertyParserHelpers::ConsumeIdent(range);
+  CSSValuePair* pair = CSSValuePair::Create(x_value, y_value,
+                                            CSSValuePair::kDropIdenticalValues);
+  return pair;
+}
+
+}  // namespace blink