add new preview watermark for docs

Change-Id: Idd63395b6b53674d0db87fbbcf37eb4864accacd
diff --git a/tools/droiddoc/templates-sdk/assets/css/default.css b/tools/droiddoc/templates-sdk/assets/css/default.css
index 47cef96..28dced5 100644
--- a/tools/droiddoc/templates-sdk/assets/css/default.css
+++ b/tools/droiddoc/templates-sdk/assets/css/default.css
@@ -2362,6 +2362,13 @@
 #doc-col {
   margin-right:0;
 }
+
+/* Uncomment this for preview release watermark
+#doc-col {
+  background: url('../images/preview.png') repeat;
+}
+*/
+
 #doc-content-container {
   margin-left: 291px
 }
diff --git a/tools/droiddoc/templates-sdk/assets/images/preview.png b/tools/droiddoc/templates-sdk/assets/images/preview.png
new file mode 100644
index 0000000..e5856db
--- /dev/null
+++ b/tools/droiddoc/templates-sdk/assets/images/preview.png
Binary files differ