cc: Move SkShader construction to a single spot in PaintShader

ui/views/painter.cc

Index: ui/views/painter.cc
diff --git a/ui/views/painter.cc b/ui/views/painter.cc
index 4c4e69f2c7f677c9f813ef067d99d21934ef90f5..ed7ff9ee348535803664c38c14a780c03659422b 100644
--- a/ui/views/painter.cc
+++ b/ui/views/painter.cc
@@ -211,8 +211,8 @@ void GradientPainter::Paint(gfx::Canvas* canvas, const gfx::Size& size) {
   else
     p[1].iset(0, size.height());
 
-  flags.setShader(cc::WrapSkShader(SkGradientShader::MakeLinear(
-      p, colors_.get(), pos_.get(), count_, SkShader::kClamp_TileMode)));
+  flags.setShader(base::MakeUnique<cc::PaintShader>(
+      p, colors_.get(), pos_.get(), count_, SkShader::kClamp_TileMode));
   flags.setStyle(cc::PaintFlags::kFill_Style);
 
   canvas->sk_canvas()->drawRect(SkRect::MakeIWH(size.width(), size.height()),