Fix potential crashes in NetworkHandler code

chromeos/network/network_sms_handler_unittest.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 "chromeos/network/network_sms_handler.h"
 
 #include <set>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 63 matching lines @@
     // first test message until RequestUpdate has been called.
     network_sms_handler_.reset(new NetworkSmsHandler());
     network_sms_handler_->Init();
     test_observer_.reset(new TestObserver());
     network_sms_handler_->AddObserver(test_observer_.get());
     network_sms_handler_->RequestUpdate(true);
     message_loop_.RunUntilIdle();
   }
 
   void TearDown() override {
+    network_sms_handler_->RemoveObserver(test_observer_.get());
     network_sms_handler_.reset();
     DBusThreadManager::Shutdown();
   }
 
  protected:
   base::MessageLoopForUI message_loop_;
   scoped_ptr<NetworkSmsHandler> network_sms_handler_;
   scoped_ptr<TestObserver> test_observer_;
 };
 
@@ skipping 10 matching lines @@
 
   // Test for messages delivered by signals.
   test_observer_->ClearMessages();
   network_sms_handler_->RequestUpdate(false);
   message_loop_.RunUntilIdle();
   EXPECT_GE(test_observer_->message_count(), 1);
   EXPECT_NE(messages.find(kMessage1), messages.end());
 }
 
 }  // namespace chromeos