MediaStream audio: Refactor 3 separate "glue" implementations into one.

content/renderer/media/tagged_list.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 CONTENT_RENDERER_MEDIA_TAGGED_LIST_H_
-#define CONTENT_RENDERER_MEDIA_TAGGED_LIST_H_
-
-#include <algorithm>
-#include <list>
-
-#include "base/logging.h"
-#include "base/macros.h"
-#include "base/memory/ref_counted.h"
-
-namespace content {
-
-// Implements the pattern of a list of items, where added items are
-// tagged, you can tag all items, and you can retrieve the list of
-// items that are tagged, which removes the tag.
-//
-// For thread safety, operations on this object should be under an
-// external lock. An internally-locked version could be created, but
-// is not needed at the moment as users already lock.
-template <class ItemType>
-class TaggedList {
- public:
-  typedef std::list<scoped_refptr<ItemType> > ItemList;
-
-  TaggedList() {}
-
-  void AddAndTag(ItemType* item) {
-    items_.push_back(item);
-    tagged_items_.push_back(item);
-  }
-
-  void TagAll() {
-    tagged_items_ = items_;
-  }
-
-  const ItemList& Items() const {
-    return items_;
-  }
-
-  // Retrieves the list of items with tags, and removes their tags.
-  //
-  // |dest| should be empty.
-  void RetrieveAndClearTags(ItemList* dest) {
-    DCHECK(dest->empty());
-    dest->swap(tagged_items_);
-  }
-
-  // Remove an item that matches a predicate. Will return a reference
-  // to it if it is found.
-  template <class UnaryPredicate>
-  scoped_refptr<ItemType> Remove(UnaryPredicate predicate) {
-    tagged_items_.remove_if(predicate);
-
-    typename ItemList::iterator it = std::find_if(
-        items_.begin(), items_.end(), predicate);
-    if (it != items_.end()) {
-      scoped_refptr<ItemType> removed_item = *it;
-      items_.erase(it);
-      return removed_item;
-    }
-
-    return NULL;
-  }
-
-  template <class UnaryPredicate>
-  bool Contains(UnaryPredicate predicate) const {
-    return std::find_if(items_.begin(), items_.end(), predicate) !=
-        items_.end();
-  }
-
-  void Clear() {
-    items_.clear();
-    tagged_items_.clear();
-  }
-
-  bool IsEmpty() const {
-    bool is_empty = items_.empty();
-    DCHECK(!is_empty || tagged_items_.empty());
-    return is_empty;
-  }
-
- private:
-  ItemList items_;
-  ItemList tagged_items_;
-
-  DISALLOW_COPY_AND_ASSIGN(TaggedList);
-};
-
-}  // namespace content
-
-#endif  // CONTENT_RENDERER_MEDIA_TAGGED_LIST_H_