Add Material Design shadow reference sample

Change-Id: I889a3f508407178c457f675c321880d869caf9ea
Reviewed-on: https://skia-review.googlesource.com/17717
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
diff --git a/shadowreference.png b/shadowreference.png
new file mode 100755
index 0000000..cca6fff
--- /dev/null
+++ b/shadowreference.png
Binary files differ