Fix google-explicit-constructor warnings.

Bug: 28341362
Change-Id: I0ce850de85e0de6a5472dd142f738856142db9ec
diff --git a/libs/gui/ISensorEventConnection.cpp b/libs/gui/ISensorEventConnection.cpp
index dc7a35c..59ecee7 100644
--- a/libs/gui/ISensorEventConnection.cpp
+++ b/libs/gui/ISensorEventConnection.cpp
@@ -40,7 +40,7 @@
 class BpSensorEventConnection : public BpInterface<ISensorEventConnection>
 {
 public:
-    BpSensorEventConnection(const sp<IBinder>& impl)
+    explicit BpSensorEventConnection(const sp<IBinder>& impl)
         : BpInterface<ISensorEventConnection>(impl)
     {
     }