Add a tiled pipe mode to SampleApp.

Using the "Pipe" checkbox in SamleApp, you can now
toggle amongst three states: no pipe, a normal pipe
(or others depending on #defines), and a tiled pipe.
You can also use shift + p to toggle.
Review URL: https://codereview.appspot.com/6303055

git-svn-id: http://skia.googlecode.com/svn/trunk@4213 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SampleApp.h b/samplecode/SampleApp.h
index c692f9d..e379994 100644
--- a/samplecode/SampleApp.h
+++ b/samplecode/SampleApp.h
@@ -157,7 +157,9 @@
     bool fMagnify;
     
     
-    bool fUsePipe;
+    SkOSMenu::TriState fPipeState;  // Mixed uses a tiled pipe
+                                    // On uses a normal pipe
+                                    // Off uses no pipe
     int  fUsePipeMenuItemID;
     bool fDebugger;