document OwnDeviceCanvas
git-svn-id: http://skia.googlecode.com/svn/trunk@4970 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/effects/SkTestImageFilters.cpp b/src/effects/SkTestImageFilters.cpp
index 0dd360b..2633b09 100755
--- a/src/effects/SkTestImageFilters.cpp
+++ b/src/effects/SkTestImageFilters.cpp
@@ -2,6 +2,13 @@
#include "SkCanvas.h"
#include "SkDevice.h"
+// Simple helper canvas that "takes ownership" of the provided device, so that
+// when this canvas goes out of scope, so will its device. Could be replaced
+// with the following:
+//
+// SkCanvas canvas(device);
+// SkAutoTUnref<SkDevice> aur(device);
+//
class OwnDeviceCanvas : public SkCanvas {
public:
OwnDeviceCanvas(SkDevice* device) : SkCanvas(device) {