Fix google-explicit-constructor warnings.

Bug: 28341362
Change-Id: I625fbab25f16282c2ea929cd16283d9d146fa17b
diff --git a/services/camera/libcameraservice/device3/Camera3ZslStream.cpp b/services/camera/libcameraservice/device3/Camera3ZslStream.cpp
index eefcb44..d753b71 100644
--- a/services/camera/libcameraservice/device3/Camera3ZslStream.cpp
+++ b/services/camera/libcameraservice/device3/Camera3ZslStream.cpp
@@ -40,7 +40,7 @@
         SELECT_NEITHER = 0,
     };
 
-    TimestampFinder(nsecs_t timestamp) : mTimestamp(timestamp) {}
+    explicit TimestampFinder(nsecs_t timestamp) : mTimestamp(timestamp) {}
     ~TimestampFinder() {}
 
     template <typename T>