Implement CSSPaintValue and add a layout test.

third_party/WebKit/Source/core/css/CSSPaintValue.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/CSSPaintValue.h"
 
 #include "core/css/CSSCustomIdentValue.h"
 #include "core/layout/LayoutObject.h"
 #include "platform/graphics/Image.h"
 #include "wtf/text/StringBuilder.h"
@@ skipping 29 matching lines @@
   return m_name->value();
 }
 
 PassRefPtr<Image> CSSPaintValue::image(const LayoutObject& layoutObject,
                                        const IntSize& size,
                                        float zoom) {
   if (!m_generator)
     m_generator = CSSPaintImageGenerator::create(
         name(), layoutObject.document(), m_paintImageGeneratorObserver);
 
-  return m_generator->paint(layoutObject, size, zoom);
+  return m_generator->paint(layoutObject, size, zoom, m_argumentVariableData);

[ikilpatrick, 2017/02/16 03:19:36]

should be able to parse the variable data inside the constructor above?

[renjieliu1, 2017/02/16 04:11:14]

do you think we can pass in the input argument types here?

 }
 
 void CSSPaintValue::Observer::paintImageGeneratorReady() {
   m_ownerValue->paintImageGeneratorReady();
 }
 
 void CSSPaintValue::paintImageGeneratorReady() {
   for (const LayoutObject* client : clients().keys()) {
     const_cast<LayoutObject*>(client)->imageChanged(
         static_cast<WrappedImagePtr>(this));
   }
 }
 
 bool CSSPaintValue::knownToBeOpaque(const LayoutObject& layoutObject) const {
   return m_generator && !m_generator->hasAlpha();
 }
 
 bool CSSPaintValue::equals(const CSSPaintValue& other) const {
   return name() == other.name() && customCSSText() == other.customCSSText();
 }
 
 DEFINE_TRACE_AFTER_DISPATCH(CSSPaintValue) {
   visitor->trace(m_name);
   visitor->trace(m_generator);
   visitor->trace(m_paintImageGeneratorObserver);
   CSSImageGeneratorValue::traceAfterDispatch(visitor);
 }
 
 }  // namespace blink