remove deprecated use of porterduff enum



git-svn-id: http://skia.googlecode.com/svn/trunk@235 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SamplePageFlip.cpp b/samplecode/SamplePageFlip.cpp
index ed4d340..29f0180 100644
--- a/samplecode/SamplePageFlip.cpp
+++ b/samplecode/SamplePageFlip.cpp
@@ -64,7 +64,7 @@
 //            SkDebugf("----- dirty [%d %d %d %d]\n", dirty.getBounds().fLeft, dirty.getBounds().fTop, dirty.getBounds().width(), dirty.getBounds().height());
             canvas.clipRegion(update.dirty());
             
-            canvas.drawColor(0, SkPorterDuff::kClear_Mode);            
+            canvas.drawColor(0, SkXfermode::kClear_Mode);            
             canvas.drawOval(oval, paint);
         }
         bounce(&x, &dx, WIDTH-OVALW);