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

third_party/WebKit/LayoutTests/csspaint/resources/paint-logging-green.js

Index: third_party/WebKit/LayoutTests/csspaint/resources/paint-logging-green.js
diff --git a/third_party/WebKit/LayoutTests/csspaint/resources/paint-logging-green.js b/third_party/WebKit/LayoutTests/csspaint/resources/paint-logging-green.js
new file mode 100644
index 0000000000000000000000000000000000000000..ab36fda68f2df0ef5c11594f07f86126ad6293e6
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/csspaint/resources/paint-logging-green.js
@@ -0,0 +1,10 @@
+// Logs the size of the geometry to the console.
+// Fills the context with a green square.
+
+registerPaint('logging-green', class {
+    paint(ctx, geom) {
+        console.log('width: ' + geom.width + ', height: ' + geom.height);
+        ctx.fillStyle = 'green';
+        ctx.fillRect(0, 0, geom.width, geom.height);
+    }
+});