Fix side-effect in DCHECK that breaks another DCHECK in JingleSession.

remoting/protocol/jingle_session.cc

Index: remoting/protocol/jingle_session.cc
diff --git a/remoting/protocol/jingle_session.cc b/remoting/protocol/jingle_session.cc
index 33938c6f53801306548c0d6f3372091cceda40c6..1778d39d86e64bbab9f9e0d0ea1e4bedf2feefda 100644
--- a/remoting/protocol/jingle_session.cc
+++ b/remoting/protocol/jingle_session.cc
@@ -85,7 +85,6 @@ JingleSession::~JingleSession() {
   STLDeleteContainerPointers(transport_info_requests_.begin(),
                              transport_info_requests_.end());
 
-  channel_multiplexer_.reset();
   DCHECK(channels_.empty());
 
   session_manager_->SessionDestroyed(this);
@@ -274,7 +273,7 @@ void JingleSession::CancelChannelCreation(const std::string& name) {
   if (it != channels_.end()) {
     DCHECK(!it->second->is_connected());
     delete it->second;
-    DCHECK(!channels_[name]);
+    DCHECK(channels_.find(name) == channels_.end());
   }
 }