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

content/renderer/media/tagged_list.h

Index: content/renderer/media/tagged_list.h
diff --git a/content/renderer/media/tagged_list.h b/content/renderer/media/tagged_list.h
new file mode 100644
index 0000000000000000000000000000000000000000..b58772c0329770d1568e51f152c30d89f0bed70a
--- /dev/null
+++ b/content/renderer/media/tagged_list.h
@@ -0,0 +1,95 @@
+// 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_