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

chrome/renderer/print_web_view_helper_mac.mm

Index: chrome/renderer/print_web_view_helper_mac.mm
diff --git a/chrome/renderer/print_web_view_helper_mac.mm b/chrome/renderer/print_web_view_helper_mac.mm
index e74739bd4add963e97ac7f496f7771ddbfbb6a08..162d0e8d18d5ea3e0cbeb571698727e4239f1e20 100644
--- a/chrome/renderer/print_web_view_helper_mac.mm
+++ b/chrome/renderer/print_web_view_helper_mac.mm
@@ -117,13 +117,12 @@ void PrintWebViewHelper::RenderPage(
       params.display_header_footer ? gfx::Rect(*page_size) : content_area;
 
   {
-    SkDevice* device = metafile->StartPageForVectorCanvas(
+    skia::RefPtr<SkDevice> device = metafile->StartPageForVectorCanvas(
         *page_size, canvas_area, scale_factor);
     if (!device)
       return;
 
-    SkRefPtr<skia::VectorCanvas> canvas = new skia::VectorCanvas(device);
-    canvas->unref();  // SkRefPtr and new both took a reference.
+    skia::RefPtr<skia::VectorCanvas> canvas = new skia::VectorCanvas(device);
     WebKit::WebCanvas* canvas_ptr = canvas.get();
     printing::MetafileSkiaWrapper::SetMetafileOnCanvas(*canvas, metafile);
     skia::SetIsDraftMode(*canvas, is_print_ready_metafile_sent_);