Flatten down to a single toolbar per window, significantly simplifying the ta...

chrome/browser/cocoa/command_observer_bridge.h

+// Copyright (c) 2009 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.
+
+#import <Cocoa/Cocoa.h>
+
+#include "chrome/browser/command_updater.h"
+
+@protocol CommandObserverProtocol;
+
+// A C++ bridge class that handles listening for updates to commands and
+// passing them back to an object that supports the protocol delcared below.
+// The observer will create one of these bridges, call ObserveCommand() on the
+// command ids it cares about, and then wait for update notifications,
+// delivered via -enabledStateChangedForCommand:enabled:. Destroying this
+// bridge will handle automatically unregistering for updates, so there's no
+// need to do that manually.
+
+class CommandObserverBridge : public CommandUpdater::CommandObserver {
+ public:
+  CommandObserverBridge(id<CommandObserverProtocol> observer,
+                        CommandUpdater* commands);
+  virtual ~CommandObserverBridge();
+
+  // Register for updates about |command|.
+  void ObserveCommand(int command);
+
+ protected:
+  // Overridden from CommandUpdater::CommandObserver
+  virtual void EnabledStateChangedForCommand(int command, bool enabled);
+
+ private:
+  id<CommandObserverProtocol> observer_;  // weak, owns me
+  CommandUpdater* commands_;  // weak
+};
+
+// Implemented by the observing Objective-C object, called when there is a
+// state change for the given command.
+@protocol CommandObserverProtocol
+- (void)enabledStateChangedForCommand:(NSInteger)command enabled:(BOOL)enabled;
+@end