Move Connection off of RefBase

The Connection class doesn't need to be inside sp<>. Convert it to use
shared_ptr. There are still a couple of places where the connection is
passed around, so we can't make it a unique_ptr.

Bug: 211379801
Test: m checkinput
Change-Id: I6755e7c9a39a015d30738c1b9052733c182628d5
diff --git a/services/inputflinger/dispatcher/Connection.h b/services/inputflinger/dispatcher/Connection.h
index 6040e9b..2929d61 100644
--- a/services/inputflinger/dispatcher/Connection.h
+++ b/services/inputflinger/dispatcher/Connection.h
@@ -27,10 +27,7 @@
 struct DispatchEntry;
 
 /* Manages the dispatch state associated with a single input channel. */
-class Connection : public RefBase {
-protected:
-    virtual ~Connection();
-
+class Connection {
 public:
     enum class Status {
         // Everything is peachy.