Add extra data to BrowserContext so that content layer and other embedders can stash data with it t…

base/supports_user_data.h

+// 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.
+
+#ifndef BASE_SUPPORTS_USER_DATA_H_
+#define BASE_SUPPORTS_USER_DATA_H_
+
+#include <map>
+
+#include "base/base_export.h"
+#include "base/memory/linked_ptr.h"
+
+namespace base {
+
+// This is a helper for classes that want to allow users to stash random data by
+// key. At destruction all the objects will be destructed.

[joth, 2012/08/23 18:11:52]

Is there some guideline when to use this vs. when to use base::PropertyBag ?
they both seem to be targeted at exactly the same use-case.

+class BASE_EXPORT SupportsUserData {
+ public:
+  SupportsUserData();
+  virtual ~SupportsUserData();
+
+  // Derive from this class and add your own data members to associate extra
+  // information with this object. Use GetUserData(key) and SetUserData()
+  class BASE_EXPORT Data {
+   public:
+    virtual ~Data() {}
+  };
+
+  // The user data allows the clients to associate data with this object.
+  // Multiple user data values can be stored under different keys.
+  // This object will TAKE OWNERSHIP of the given data pointer, and will
+  // delete the object if it is changed or the object is destroyed.
+  Data* GetUserData(const void* key) const;
+  void SetUserData(const void* key, Data* data);
+
+ private:
+  typedef std::map<const void*, linked_ptr<Data> > DataMap;
+
+  // Externally-defined data accessible by key
+  DataMap user_data_;
+
+  DISALLOW_COPY_AND_ASSIGN(SupportsUserData);
+};
+
+}  // namespace base
+
+#endif  // BASE_SUPPORTS_USER_DATA_H_