Remove SkRefPtr

(resubmit of https://codereview.appspot.com/7030059/)
TBR=junov@google.com

Review URL: https://codereview.appspot.com/7030065

git-svn-id: http://skia.googlecode.com/svn/trunk@7030 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SampleTextureDomain.cpp b/samplecode/SampleTextureDomain.cpp
index 07dcb40..926a413 100644
--- a/samplecode/SampleTextureDomain.cpp
+++ b/samplecode/SampleTextureDomain.cpp
@@ -61,10 +61,10 @@
         // the constrainted texture domain.
         // Note:  GPU-backed bitmaps follow a different rendering path
         // when copying from one GPU device to another.
-        SkRefPtr<SkDevice> primaryDevice(canvas->getDevice());
-        SkRefPtr<SkDevice> secondDevice(canvas->createCompatibleDevice(
+        SkAutoTUnref<SkDevice> primaryDevice(canvas->getDevice());
+        SkSafeRef(primaryDevice.get());
+        SkAutoTUnref<SkDevice> secondDevice(canvas->createCompatibleDevice(
                 SkBitmap::kARGB_8888_Config, 5, 5, true));
-        secondDevice->unref();
         SkCanvas secondCanvas(secondDevice.get());
 
         srcRect.setXYWH(1, 1, 3, 3);