Split out String, URI and CustomIdent from CSSPrimitiveValue

Source/core/css/CSSStringValue.cpp

Index: Source/core/css/CSSStringValue.cpp
diff --git a/Source/core/css/CSSStringValue.cpp b/Source/core/css/CSSStringValue.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..e12743fddaf43225c8323eb96b05e4e6d489a254
--- /dev/null
+++ b/Source/core/css/CSSStringValue.cpp
@@ -0,0 +1,37 @@
+// Copyright 2015 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 "config.h"
+#include "core/css/CSSStringValue.h"
+
+#include "core/css/CSSMarkup.h"
+
+namespace blink {
+
+CSSStringValue::~CSSStringValue()
+{
+    if (m_string)
+        m_string->deref();
+}
+
+String CSSStringValue::customCSSText() const
+{
+    switch (m_serializationType) {
+    case SerializeAsString:
+        return serializeString(m_string);
+    case SerializeAsCustomIdentifier:
+        return quoteCSSStringIfNeeded(m_string);
+    case SerializeAsURI:
+        return "url(" + quoteCSSURLIfNeeded(m_string) + ")";
+    }
+    ASSERT_NOT_REACHED();
+    return String();
+}
+
+DEFINE_TRACE_AFTER_DISPATCH(CSSStringValue)
+{
+    CSSValue::traceAfterDispatch(visitor);
+}
+
+}