Refactor SignalStrategy so that it can be reused for multiple connections.

remoting/host/heartbeat_sender_unittest.cc

Index: remoting/host/heartbeat_sender_unittest.cc
diff --git a/remoting/host/heartbeat_sender_unittest.cc b/remoting/host/heartbeat_sender_unittest.cc
index 4c3390a8046ec282a39c0f587dc6c70bdcfc2e90..b1de98b47a2bf6750e57ce1ea9f342feae79ddb5 100644
--- a/remoting/host/heartbeat_sender_unittest.cc
+++ b/remoting/host/heartbeat_sender_unittest.cc
@@ -64,12 +64,14 @@ TEST_F(HeartbeatSenderTest, DoSendStanza) {
   ASSERT_TRUE(heartbeat_sender->Init());
 
   XmlElement* sent_iq = NULL;
+  EXPECT_CALL(signal_strategy_, GetLocalJid())
+      .WillRepeatedly(Return(kTestJid));
   EXPECT_CALL(signal_strategy_, GetNextId())
       .WillOnce(Return(kStanzaId));
   EXPECT_CALL(signal_strategy_, SendStanza(NotNull()))
       .WillOnce(DoAll(SaveArg<0>(&sent_iq), Return(true)));
 
-  heartbeat_sender->OnSignallingConnected(&signal_strategy_, kTestJid);
+  heartbeat_sender->OnSignallingConnected(&signal_strategy_);
   message_loop_.RunAllPending();
 
   scoped_ptr<XmlElement> stanza(sent_iq);