Add skia::RefPtr class to wrap ref counted classes from Skia.

ash/wm/gestures/long_press_affordance_handler.cc

Index: ash/wm/gestures/long_press_affordance_handler.cc
diff --git a/ash/wm/gestures/long_press_affordance_handler.cc b/ash/wm/gestures/long_press_affordance_handler.cc
index 25d3a4dcea3a377590549efea307dc89751a3893..3127791ffedc0203070959faec791cf158e30e91 100644
--- a/ash/wm/gestures/long_press_affordance_handler.cc
+++ b/ash/wm/gestures/long_press_affordance_handler.cc
@@ -105,7 +105,7 @@ void PaintAffordanceGlow(gfx::Canvas* canvas,
   int radius = (end_radius + start_radius) / 2;
   int glow_width = end_radius - start_radius;
   sk_center.iset(center.x(), center.y());
-  SkShader* shader = SkGradientShader::CreateTwoPointRadial(
+  skia::RefPtr<SkShader> shader = SkGradientShader::CreateTwoPointRadial(
       sk_center,
       SkIntToScalar(start_radius),
       sk_center,
@@ -118,9 +118,8 @@ void PaintAffordanceGlow(gfx::Canvas* canvas,
   SkPaint paint;
   paint.setStyle(SkPaint::kStroke_Style);
   paint.setStrokeWidth(glow_width);
-  paint.setShader(shader);
+  paint.setShader(shader.get());
   paint.setAntiAlias(true);
-  shader->unref();
   SkPath arc_path;
   arc_path.addArc(SkRect::MakeXYWH(center.x() - radius,
                                    center.y() - radius,