Add new API to compare certs of two UIDs.
diff --git a/test-runner/android/test/mock/MockPackageManager.java b/test-runner/android/test/mock/MockPackageManager.java
index 63a177e..4a50c5d 100644
--- a/test-runner/android/test/mock/MockPackageManager.java
+++ b/test-runner/android/test/mock/MockPackageManager.java
@@ -139,6 +139,11 @@
     }
 
     @Override
+    public int checkSignatures(int uid1, int uid2) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
     public String[] getPackagesForUid(int uid) {
         throw new UnsupportedOperationException();
     }