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diff --git a/chrome/browser/command_updater.h b/chrome/browser/command_updater.h
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+// Copyright (c) 2006-2008 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 CHROME_BROWSER_COMMAND_UPDATER_H_
+#define CHROME_BROWSER_COMMAND_UPDATER_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/hash_tables.h"
+#include "base/observer_list.h"
+
+////////////////////////////////////////////////////////////////////////////////
+//
+// CommandUpdater class
+//
+//   This object manages the enabled state of a set of commands. Observers
+//   register to listen to changes in this state so they can update their
+//   presentation.
+//
+class CommandUpdater {
+ public:
+  // A Delegate object implements this interface so that it can execute commands
+  // when needed.
+  class CommandUpdaterDelegate {
+   public:
+    // Perform the action associated with the command with the specified ID.
+    virtual void ExecuteCommand(int id) = 0;
+  };
+
+  // Create a CommandUpdater with a CommandUpdaterDelegate to handle execution
+  // of specific commands.
+  explicit CommandUpdater(CommandUpdaterDelegate* handler);
+  virtual ~CommandUpdater();
+
+  // Returns true if the specified command ID is supported.
+  bool SupportsCommand(int id) const;
+
+  // Returns true if the specified command ID is enabled. The command ID must be
+  // supported by this updater.
+  bool IsCommandEnabled(int id) const;
+
+  // Performs the action associated with this command ID.
+  // TODO(beng): get rid of this since it's effectively just a pass-thru and the
+  // call sites would be better off using more well defined delegate interfaces.
+  void ExecuteCommand(int id);
+
+  // An Observer interface implemented by objects that want to be informed when
+  // the state of a particular command ID is modified.
+  class CommandObserver {
+   public:
+    // Notifies the observer that the enabled state has changed for the
+    // specified command id.
+    virtual void EnabledStateChangedForCommand(int id, bool enabled) = 0;
+  };
+
+  // Adds an observer to the state of a particular command. If the command does
+  // not exist, it is created, initialized to false.
+  void AddCommandObserver(int id, CommandObserver* observer);
+
+  // Removes an observer to the state of a particular command.
+  void RemoveCommandObserver(int id, CommandObserver* observer);
+
+  // Notify all observers of a particular command that the command has been
+  // enabled or disabled. If the command does not exist, it is created and
+  // initialized to |state|. This function is very lightweight if the command
+  // state has not changed.
+  void UpdateCommandEnabled(int id, bool state);
+
+ private:
+  // A piece of data about a command - whether or not it is enabled, and a list
+  // of objects that observe the enabled state of this command.
+  class Command {
+   public:
+    bool enabled;
+    ObserverList<CommandObserver> observers;
+
+    Command() : enabled(true) {}
+  };
+
+  // Get a Command node for a given command ID, creating an entry if it doesn't
+  // exist if desired.
+  Command* GetCommand(int id, bool create);
+
+  // The delegate is responsible for executing commands.
+  CommandUpdaterDelegate* delegate_;
+
+  // This is a map of command IDs to states and observer lists
+  typedef base::hash_map<int, Command*> CommandMap;
+  CommandMap commands_;
+
+  CommandUpdater();
+  DISALLOW_EVIL_CONSTRUCTORS(CommandUpdater);
+};
+
+#endif // CHROME_BROWSER_COMMAND_UPDATER_H_