skia_svg_render use white color as background.

examples/skia_svg_render.cc

@@ -37,6 +37,8 @@ int main(int argc, char *argv[]) {
         return 1;
     }
 
+    canvas->clear(SkColors::kWhite);
+
     auto fDom = SkSVGDOM::MakeFromStream(svgStream);
     fDom->setContainerSize(SkSize::Make(width, height));
     fDom->render(canvas.get());