Add new repo backports.

Reference document -
https://docs.google.com/a/google.com/document/d/1ZyDhRqOuSpXZ6UZCcQBZK43obDviJZJH4_hZkFBP0Vk/edit

Change-Id: I4c5837d4570c9b7426fdaa244dbd8acb4fa2c0be
diff --git a/default.xml b/default.xml
index 82db61d..7b1872f 100644
--- a/default.xml
+++ b/default.xml
@@ -69,6 +69,7 @@
   <project name="vendor/mindspeed/drivers"/>
   <project name="vendor/netflix/nrd"/>
   <project name="vendor/ookla"/>
+  <project name="vendor/opensource/backports"/>
   <project name="vendor/opensource/bluez"/>
   <project name="vendor/opensource/dial"/>
   <project name="vendor/opensource/ffmpeg"/>