Fix google-explicit-constructor warnings.

Bug: 28341362
Change-Id: I625fbab25f16282c2ea929cd16283d9d146fa17b
diff --git a/media/libmedia/IResourceManagerClient.cpp b/media/libmedia/IResourceManagerClient.cpp
index b3f56e8..1fea479 100644
--- a/media/libmedia/IResourceManagerClient.cpp
+++ b/media/libmedia/IResourceManagerClient.cpp
@@ -31,7 +31,7 @@
 class BpResourceManagerClient: public BpInterface<IResourceManagerClient>
 {
 public:
-    BpResourceManagerClient(const sp<IBinder> &impl)
+    explicit BpResourceManagerClient(const sp<IBinder> &impl)
         : BpInterface<IResourceManagerClient>(impl)
     {
     }