Replace more ObserverList with base::ObserverList.

components/proximity_auth/logging/log_buffer.h

 // Copyright 2015 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 COMPONENTS_PROXIMITY_AUTH_LOGGING_LOG_BUFFER_H
 #define COMPONENTS_PROXIMITY_AUTH_LOGGING_LOG_BUFFER_H
 
 #include <list>
 
 #include "base/logging.h"
@@ skipping 53 matching lines @@
   size_t MaxBufferSize() const;
 
   // Returns the list logs in the buffer, sorted chronologically.
   const std::list<LogMessage>* logs() { return &log_messages_; }
 
  private:
   // The messages currently in the buffer.
   std::list<LogMessage> log_messages_;
 
   // List of observers.
-  ObserverList<Observer> observers_;
+  base::ObserverList<Observer> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(LogBuffer);
 };
 
 }  // namespace proximity_auth
 
 #endif  // COMPONENTS_PROXIMITY_AUTH_LOGGING_LOG_BUFFER_H