Invalidate ChromotingJniInstance's WeakPtr on network thread

remoting/client/jni/chromoting_jni_instance.h

 // Copyright 2013 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.
 
 #ifndef REMOTING_CLIENT_CHROMOTING_JNI_INSTANCE_H_
 #define REMOTING_CLIENT_CHROMOTING_JNI_INSTANCE_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 37 matching lines @@
                         const std::string& auth_token,
                         const std::string& host_jid,
                         const std::string& host_id,
                         const std::string& host_pubkey,
                         const std::string& pairing_id,
                         const std::string& pairing_secret,
                         const std::string& capabilities,
                         const std::string& flags);
 
   // Terminates the current connection (if it hasn't already failed) and cleans
-  // up. Must be called before destruction.
+  // up. The instance will no longer be valid after calling this function.
+  // Must be called before destruction.
   void Disconnect();
 
   // Requests the android app to fetch a third-party token.
   void FetchThirdPartyToken(
       const std::string& host_public_key,
       const std::string& token_url,
       const std::string& scope,
       const protocol::ThirdPartyTokenFetchedCallback& token_fetched_callback);
 
   // Called by the android app when the token is fetched.
@@ skipping 125 matching lines @@
   friend class base::RefCountedThreadSafe<ChromotingJniInstance>;
 
   base::WeakPtrFactory<ChromotingJniInstance> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromotingJniInstance);
 };
 
 }  // namespace remoting
 
 #endif