Fix chromoting client crash.

remoting/client/plugin/chromoting_instance.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "remoting/client/plugin/chromoting_instance.h"
 
 #include <string>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 598 matching lines @@
     done_event.Wait();
     client_.reset();
   }
 
   // Disconnect the input pipeline and teardown the connection.
   mouse_input_filter_.set_input_stub(NULL);
   host_connection_.reset();
 }
 
 void ChromotingInstance::OnIncomingIq(const std::string& iq) {
-  xmpp_proxy_->OnIq(iq);
+  // Just ignore the message if it's received before Connect() is called. It's
+  // likely to be a leftover from a previous session, so it's safe to ignore it.
+  if (xmpp_proxy_)
+    xmpp_proxy_->OnIq(iq);
 }
 
 void ChromotingInstance::ReleaseAllKeys() {
   if (IsConnected())
     input_tracker_.ReleaseAll();
 }
 
 void ChromotingInstance::InjectKeyEvent(const protocol::KeyEvent& event) {
   // Inject after the KeyEventMapper, so the event won't get mapped or trapped.
   if (IsConnected())
@@ skipping 237 matching lines @@
                                       url_components.scheme.len);
   return url_scheme == kChromeExtensionUrlScheme;
 }
 
 bool ChromotingInstance::IsConnected() {
   return host_connection_.get() &&
     (host_connection_->state() == protocol::ConnectionToHost::CONNECTED);
 }
 
 }  // namespace remoting