Hook up CSSPaintValue::image to CSS Paint API callback.

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

Index: third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.h
diff --git a/third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.h b/third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.h
index 9c768b7377e226930b370f2b949be40d199d3c6b..1e8a09d69dc89585cb8e825978666f64d7542939 100644
--- a/third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.h
+++ b/third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.h
@@ -12,6 +12,7 @@
 
 namespace blink {
 
+class Image;
 class ScriptState;
 
 class CSSPaintDefinition final : public GarbageCollectedFinalized<CSSPaintDefinition> {
@@ -19,6 +20,10 @@ public:
     static RawPtr<CSSPaintDefinition> create(ScriptState*, v8::Local<v8::Function> constructor, v8::Local<v8::Function> paint);
     virtual ~CSSPaintDefinition();
 
+    PassRefPtr<Image> paint(const IntSize&);

[chrishtr, 2016/04/06 18:55:20]

This class is under-documented.

Please also add Markdown documentation for this directory, explaining
the class structure and how it implements the CSS paint API. And
link to it from README.md in core/paint/

[ikilpatrick, 2016/04/07 23:03:00]

PTAL.

+    v8::Local<v8::Object> paintInstance();
+    ScriptState* getScriptState() const { return m_scriptState.get(); }
+
     v8::Local<v8::Function> paintFunctionForTesting(v8::Isolate* isolate) { return m_paint.newLocal(isolate); }
 
     DEFINE_INLINE_TRACE() { };
@@ -33,6 +38,11 @@ private:
     // PaintWorkletGlobalScope.
     ScopedPersistent<v8::Function> m_constructor;
     ScopedPersistent<v8::Function> m_paint;
+
+    // At the moment there is only ever one instance of a paint class per type.
+    // This is a weak reference, CSSPaintImageGeneratorImpl holds a persistent
+    // reference which keeps it alive.
+    ScopedPersistent<v8::Object> m_instance;
 };
 
 } // namespace blink