Fix google-explicit-constructor warnings.

Bug: 28341362
Change-Id: I83bb2282249ecd4e39347b90f5fb53788e1fff5b
diff --git a/services/batteryservice/IBatteryPropertiesRegistrar.cpp b/services/batteryservice/IBatteryPropertiesRegistrar.cpp
index 46934e0..1fdda43 100644
--- a/services/batteryservice/IBatteryPropertiesRegistrar.cpp
+++ b/services/batteryservice/IBatteryPropertiesRegistrar.cpp
@@ -28,7 +28,7 @@
 
 class BpBatteryPropertiesRegistrar : public BpInterface<IBatteryPropertiesRegistrar> {
 public:
-    BpBatteryPropertiesRegistrar(const sp<IBinder>& impl)
+    explicit BpBatteryPropertiesRegistrar(const sp<IBinder>& impl)
         : BpInterface<IBatteryPropertiesRegistrar>(impl) {}
 
         void registerListener(const sp<IBatteryPropertiesListener>& listener) {