Remove ash::ScopedObserverWithDuplicatedSources

ash/shelf/scoped_observer_with_duplicated_sources.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 ASH_SHELF_SCOPED_OBSERVER_WITH_DUPLICATED_SOURCES_H_
-#define ASH_SHELF_SCOPED_OBSERVER_WITH_DUPLICATED_SOURCES_H_
-
-#include <map>
-
-#include "base/logging.h"
-#include "base/macros.h"
-
-// ScopedObserverWithDuplicatedSources is used to keep track of the set of
-// sources an object has attached itself to as an observer. When
-// ScopedObserverWithDuplicatedSources is destroyed it removes the object as an
-// observer from all sources it has been added to.
-// ScopedObserverWithDuplicatedSources adds |observer| once for a particular
-// source, no matter how many times Add() is invoked. Additionaly |observer| is
-// only removed once Remove() is invoked the same number of times as Add().
-
-template <class Source, class Observer>
-class ScopedObserverWithDuplicatedSources {
- public:
-  explicit ScopedObserverWithDuplicatedSources(Observer* observer)
-      : observer_(observer) {}
-
-  ~ScopedObserverWithDuplicatedSources() {
-    typename SourceToAddCountMap::const_iterator iter =
-        counted_sources_.begin();
-    for (; iter != counted_sources_.end(); ++iter)
-      iter->first->RemoveObserver(observer_);
-  }
-
-  // Adds the object passed to the constructor only once as an observer on
-  // |source|.
-  void Add(Source* source) {
-    if (counted_sources_.find(source) == counted_sources_.end())
-      source->AddObserver(observer_);
-    counted_sources_[source]++;
-  }
-
-  // Only remove the object passed to the constructor as an observer from
-  // |source| when Remove() is invoked the same number of times as Add().
-  void Remove(Source* source) {
-    typename SourceToAddCountMap::iterator iter = counted_sources_.find(source);
-    DCHECK(iter != counted_sources_.end() && iter->second > 0);
-
-    if (--iter->second == 0) {
-      counted_sources_.erase(source);
-      source->RemoveObserver(observer_);
-    }
-  }
-
-  bool IsObserving(Source* source) const {
-    return counted_sources_.find(source) != counted_sources_.end();
-  }
-
- private:
-  typedef std::map<Source*, int> SourceToAddCountMap;
-
-  Observer* observer_;
-
-  // Map Source and its adding count.
-  std::map<Source*, int> counted_sources_;
-
-  DISALLOW_COPY_AND_ASSIGN(ScopedObserverWithDuplicatedSources);
-};
-
-#endif  // ASH_SHELF_SCOPED_OBSERVER_WITH_DUPLICATED_SOURCES_H_