Fix google-explicit-constructor warnings.

Bug: 28341362
Change-Id: Ibdd6a210bb7ff228e3624cc319169f77aca3b51e
diff --git a/native/android/choreographer.cpp b/native/android/choreographer.cpp
index e35c85b..c3629da 100644
--- a/native/android/choreographer.cpp
+++ b/native/android/choreographer.cpp
@@ -64,7 +64,7 @@
     virtual ~Choreographer() = default;
 
 private:
-    Choreographer(const sp<Looper>& looper);
+    explicit Choreographer(const sp<Looper>& looper);
     Choreographer(const Choreographer&) = delete;
 
     virtual void dispatchVsync(nsecs_t timestamp, int32_t id, uint32_t count);