android: android-8.1.0_r15

Change-Id: I8f8f55987b8c75e7602d4a3e5afc719291ab1641
diff --git a/default.xml b/default.xml
index 4a0c68b..4e048b6 100644
--- a/default.xml
+++ b/default.xml
@@ -3,7 +3,7 @@
   <remote  name="aosp"
            fetch="https://android.googlesource.com"
            review="https://android-review.googlesource.com/" />
-  <default revision="refs/tags/android-8.1.0_r11"
+  <default revision="refs/tags/android-8.1.0_r15"
            remote="aosp"
            sync-c="true"
            sync-j="12" />