Add broken assert in performance tests of DocumentsUI.

Bug: 27370274
Change-Id: Ibdacd82b384d37d76527c622d9986876fe84fcbd
diff --git a/perf-tests/src/com/android/documentsui/FilesActivityPerfTest.java b/perf-tests/src/com/android/documentsui/FilesActivityPerfTest.java
index 05fd2f7..bf056f1 100644
--- a/perf-tests/src/com/android/documentsui/FilesActivityPerfTest.java
+++ b/perf-tests/src/com/android/documentsui/FilesActivityPerfTest.java
@@ -121,7 +121,7 @@
                 activity.removeEventListener(listener);
             }
 
-            assertEquals(i, measurements.size());
+            assertEquals(i + 1, measurements.size());
 
             // Go back to the empty root.
             bots.roots.openRoot(STRESS_ROOT_0_ID);