Fixing missing file in build rule

Change-Id: I272bfd9516a716637c5a245e13bd3a3f2c334f5c
diff --git a/Android.bp b/Android.bp
index aefc1f0..2608280 100644
--- a/Android.bp
+++ b/Android.bp
@@ -23,6 +23,7 @@
     srcs: [
         "tests/tapl/**/*.java",
         "quickstep/src/com/android/quickstep/SwipeUpSetting.java",
+        "src/com/android/launcher3/util/SecureSettingsObserver.java",
         "src/com/android/launcher3/TestProtocol.java",
     ],
     platform_apis: true,