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

ui/native_theme/native_theme_base.cc

Index: ui/native_theme/native_theme_base.cc
diff --git a/ui/native_theme/native_theme_base.cc b/ui/native_theme/native_theme_base.cc
index fa6151fdff828bf944125ca58910f675d19b094b..98fcbf7130243fe296e35c5d156c6098ba188800 100644
--- a/ui/native_theme/native_theme_base.cc
+++ b/ui/native_theme/native_theme_base.cc
@@ -576,12 +576,11 @@ SkRect NativeThemeBase::PaintCheckboxRadioNewCommon(
   else /* kNormal */
     startEndColors = kCheckboxGradientColors;
   SkColor colors[3] = {startEndColors[0], startEndColors[0], startEndColors[1]};
-  SkShader* shader = SkGradientShader::CreateLinear(
+  skia::RefPtr<SkShader> shader = SkGradientShader::CreateLinear(
       gradient_bounds, colors, NULL, 3, SkShader::kClamp_TileMode, NULL);
   SkPaint paint;
   paint.setAntiAlias(true);
-  paint.setShader(shader);
-  shader->unref();
+  paint.setShader(shader.get());
   paint.setStyle(SkPaint::kFill_Style);
   canvas->drawRoundRect(skrect, borderRadius, borderRadius, paint);
   paint.setShader(NULL);
@@ -725,12 +724,11 @@ void NativeThemeBase::PaintButton(SkCanvas* canvas,
   colors[0] = light_color;
   colors[1] = base_color;
 
-  SkShader* shader = SkGradientShader::CreateLinear(
+  skia::RefPtr<SkShader> shader = SkGradientShader::CreateLinear(
       gradient_bounds, colors, NULL, 2, SkShader::kClamp_TileMode, NULL);
   paint.setStyle(SkPaint::kFill_Style);
   paint.setAntiAlias(true);
-  paint.setShader(shader);
-  shader->unref();
+  paint.setShader(shader.get());
 
   canvas->drawRoundRect(skrect, SkIntToScalar(1), SkIntToScalar(1), paint);
   paint.setShader(NULL);