Implements CSSPropertyAPI for the text-underline-position property.

third_party/WebKit/Source/core/css/properties/CSSPropertyAPITextUnderlinePosition.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/CSSPropertyAPITextUnderlinePosition.h"
+
+#include "core/css/parser/CSSPropertyParserHelpers.h"
+#include "platform/RuntimeEnabledFeatures.h"
+
+namespace blink {
+
+const CSSValue* CSSPropertyAPITextUnderlinePosition::parseSingleValue(
+    CSSParserTokenRange& range,
+    const CSSParserContext& context) {
+  // auto | [ under || [ left | right ] ], but we only support auto | under
+  // for now
+  DCHECK(RuntimeEnabledFeatures::css3TextDecorationsEnabled());
+  // auto | [ under || [ left | right ] ], but we only support auto | under
+  // for now
+  DCHECK(RuntimeEnabledFeatures::css3TextDecorationsEnabled());
+  return CSSPropertyParserHelpers::consumeIdent<CSSValueAuto, CSSValueUnder>(
+      range);
+}
+
+}  // namespace blink