Check stats dir instead of making one

Test: TH
Fix: 320842133
Change-Id: I3efa5186e5e2c39ec6c7430dfd726ac86ffcb954
diff --git a/service-t/src/com/android/metrics/NetworkStatsMetricsLogger.java b/service-t/src/com/android/metrics/NetworkStatsMetricsLogger.java
index 3ed21a2..08a8603 100644
--- a/service-t/src/com/android/metrics/NetworkStatsMetricsLogger.java
+++ b/service-t/src/com/android/metrics/NetworkStatsMetricsLogger.java
@@ -109,7 +109,7 @@
      */
     private static Pair<Integer, Integer> getStatsFilesAttributes(
             @Nullable File statsDir, @NonNull String prefix) {
-        if (statsDir == null) return new Pair<>(0, 0);
+        if (statsDir == null || !statsDir.isDirectory()) return new Pair<>(0, 0);
 
         // Only counts the matching files.
         // The files are named in the following format:
@@ -118,9 +118,6 @@
         // See FileRotator#FileInfo for more detail.
         final Pattern pattern = Pattern.compile("^" + prefix + "\\.[0-9]+-[0-9]*$");
 
-        // Ensure that base path exists.
-        statsDir.mkdirs();
-
         int totalFiles = 0;
         int totalBytes = 0;
         for (String name : emptyIfNull(statsDir.list())) {