pdfviewer: All NulCanvas (does not draw operations), TrackDevice (trackes what pixels have been changed)

Review URL: https://codereview.chromium.org/19793006

git-svn-id: http://skia.googlecode.com/svn/trunk@10236 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/experimental/PdfViewer/SkNulCanvas.cpp b/experimental/PdfViewer/SkNulCanvas.cpp
new file mode 100644
index 0000000..7bd69f0
--- /dev/null
+++ b/experimental/PdfViewer/SkNulCanvas.cpp
@@ -0,0 +1 @@
+#include "SkNulCanvas.h"