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..93aeb06dc3463961d3dbc0678ad2a77d192d6f15 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());
@@ -99,15 +103,21 @@ PassRefPtr<Image> CSSPaintDefinition::paint(const LayoutObject& layoutObject,
   v8::Local<v8::Value> argv[] = {
       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);
 
   v8::TryCatch block(isolate);
   block.SetVerbose(true);
 
-  V8ScriptRunner::callFunction(paint, m_scriptState->getExecutionContext(),
-                               instance, 3, argv, isolate);
+  if (RuntimeEnabledFeatures::cssPaintAPIArgumentsEnabled()) {
+    V8ScriptRunner::callFunction(paint, m_scriptState->getExecutionContext(),
+                                 instance, 4, argv, isolate);
+  } else {
+    V8ScriptRunner::callFunction(paint, m_scriptState->getExecutionContext(),
+                                 instance, 3, argv, isolate);
+  }
 
   // The paint function may have produced an error, in which case produce an
   // invalid image.