Use skia::RefPtr in place of manual ref-counting for Skia types.

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index b09cc01adae39af445dc9620bf65e76b9fcce054..a3f2dc5fe4850f9eb0b8dce43c9aa3f4bf79886e 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -674,10 +674,11 @@ void RenderWidget::PaintRect(const gfx::Rect& rect,
   // If there is a custom background, tile it.
   if (!background_.empty()) {
     SkPaint paint;
-    SkShader* shader = SkShader::CreateBitmapShader(background_,
-                                                    SkShader::kRepeat_TileMode,
-                                                    SkShader::kRepeat_TileMode);
-    paint.setShader(shader)->unref();
+    skia::RefPtr<SkShader> shader = skia::AdoptRef(
+        SkShader::CreateBitmapShader(background_,
+                                     SkShader::kRepeat_TileMode,
+                                     SkShader::kRepeat_TileMode));
+    paint.setShader(shader.get());
 
     // Use kSrc_Mode to handle background_ transparency properly.
     paint.setXfermodeMode(SkXfermode::kSrc_Mode);