Add SkTileGridPicture SampleApp playback support.

SampleApp already supports switching to a bbox hierarchy playback mode
('b' shortcut). This CL adds an SkTileGridPicture bbox mode.

R=reed@google.com, robertphillips@google.com, fmalita@google.com

Author: fmalita@chromium.org

Review URL: https://codereview.chromium.org/108513006

git-svn-id: http://skia.googlecode.com/svn/trunk@12613 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/samplecode/SampleApp.h b/samplecode/SampleApp.h
index 3e42dd6..106931c 100644
--- a/samplecode/SampleApp.h
+++ b/samplecode/SampleApp.h
@@ -243,6 +243,7 @@
     void installDrawFilter(SkCanvas*);
     int findByTitle(const char*);
     void listTitles();
+    SkSize tileSize() const;
 
     typedef SkOSWindow INHERITED;
 };