Implement CSSPaintValue and add a layout test.

third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.cpp

Index: third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.cpp
diff --git a/third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.cpp b/third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.cpp
index 5a37f56c481afe7ba76b546e4f2899b80fb06166..2a4c8a414f2b554bd6d8f2f7ac1e512047895f59 100644
--- a/third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.cpp
+++ b/third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.cpp
@@ -66,9 +66,13 @@ CSSPaintDefinition::CSSPaintDefinition(
 
 CSSPaintDefinition::~CSSPaintDefinition() {}
 
-PassRefPtr<Image> CSSPaintDefinition::paint(const LayoutObject& layoutObject,
-                                            const IntSize& size,
-                                            float zoom) {
+PassRefPtr<Image> CSSPaintDefinition::paint(
+    const LayoutObject& layoutObject,
+    const IntSize& size,
+    float zoom,
+    const CSSStyleValueVector* paintArguments) {
+  DCHECK(paintArguments);
+
   const IntSize specifiedSize = getSpecifiedSize(size, zoom);
 
   ScriptState::Scope scope(m_scriptState.get());
@@ -99,7 +103,8 @@ PassRefPtr<Image> CSSPaintDefinition::paint(const LayoutObject& layoutObject,
   v8::Local<v8::Value> argv[] = {

[ikilpatrick, 2017/02/21 17:40:36]

you'll probably need to surround this with  "if
(RuntimeEnabledFeature::isInput...)" to switch between 3 and 4 arg versions.

[renjieliu1, 2017/02/22 04:47:54]

Done.

       ToV8(renderingContext, m_scriptState->context()->Global(), isolate),
       ToV8(paintSize, m_scriptState->context()->Global(), isolate),
-      ToV8(styleMap, m_scriptState->context()->Global(), isolate)};
+      ToV8(styleMap, m_scriptState->context()->Global(), isolate),
+      ToV8(*paintArguments, m_scriptState->context()->Global(), isolate)};
 
   v8::Local<v8::Function> paint = m_paint.newLocal(isolate);
 
@@ -107,7 +112,7 @@ PassRefPtr<Image> CSSPaintDefinition::paint(const LayoutObject& layoutObject,
   block.SetVerbose(true);
 
   V8ScriptRunner::callFunction(paint, m_scriptState->getExecutionContext(),
-                               instance, 3, argv, isolate);
+                               instance, 4, argv, isolate);
 
   // The paint function may have produced an error, in which case produce an
   // invalid image.