Standardize usage of virtual/override/final specifiers in jingle/.

jingle/notifier/listener/push_client_unittest.cc

Index: jingle/notifier/listener/push_client_unittest.cc
diff --git a/jingle/notifier/listener/push_client_unittest.cc b/jingle/notifier/listener/push_client_unittest.cc
index 0357cf260f4d09fd0d8de936b6c7aa09f51618b9..5296663d3cf5e18ac9b9e70dc380f228ef6dab58 100644
--- a/jingle/notifier/listener/push_client_unittest.cc
+++ b/jingle/notifier/listener/push_client_unittest.cc
@@ -26,7 +26,7 @@ class PushClientTest : public testing::Test {
             message_loop_.message_loop_proxy());
   }
 
-  virtual ~PushClientTest() {}
+  ~PushClientTest() override {}
 
   // The sockets created by the XMPP code expect an IO loop.
   base::MessageLoopForIO message_loop_;