Add per-file OWNERS for BatteryStats

Test: N/A

Change-Id: Ie9eef7eed7f097113074c3c5f3f7a7084a55f97b
diff --git a/BATTERY_STATS_OWNERS b/BATTERY_STATS_OWNERS
new file mode 100644
index 0000000..7728975
--- /dev/null
+++ b/BATTERY_STATS_OWNERS
@@ -0,0 +1,4 @@
+# OWNERS of BatteryStats related files
+bookatz@google.com
+dplotnikov@google.com
+mwachens@google.com