[Mac] Move UI item validation to UserInterfaceItemCommandHandler.

ui/base/cocoa/command_dispatcher.h

 // Copyright 2015 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 UI_BASE_COCOA_COMMAND_DISPATCHER_H_
 #define UI_BASE_COCOA_COMMAND_DISPATCHER_H_
 
 #import <Cocoa/Cocoa.h>
 
 #import "base/mac/scoped_nsobject.h"
 #include "ui/base/ui_base_export.h"
 
 @protocol CommandDispatcherDelegate;
 @protocol CommandDispatchingWindow;
+@protocol UserInterfaceItemCommandHandler;
 
 // CommandDispatcher guides the processing of key events to ensure key commands
 // are executed in the appropriate order. In particular, it allows a first
 // responder implementing CommandDispatcherTarget to handle an event
 // asynchronously and return unhandled events via -redispatchKeyEvent:. An
 // NSWindow can use CommandDispatcher by implementing CommandDispatchingWindow
 // and overriding -[NSWindow performKeyEquivalent:] and -[NSWindow sendEvent:]
 // to call the respective CommandDispatcher methods.
 UI_BASE_EXPORT @interface CommandDispatcher : NSObject
 
@@ skipping 49 matching lines @@
 // Called after the default -performKeyEquivalent:. |window| is the
 // CommandDispatchingWindow that owns CommandDispatcher.
 - (BOOL)postPerformKeyEquivalent:(NSEvent*)event window:(NSWindow*)window;
 
 @end
 
 // The set of methods an NSWindow subclass needs to implement to use
 // CommandDispatcher.
 @protocol CommandDispatchingWindow
 
+// If set, NSUserInterfaceItemValidations for -commandDispatch: and
+// -commandDispatchUsingKeyModifiers: will be redirected to the command handler.
+// Retains |commandHandler|.
+-(void)setCommandHandler:(id<UserInterfaceItemCommandHandler>) commandHandler;
+
 // This can be implemented with -[CommandDispatcher redispatchKeyEvent:]. It's
 // so that callers can simply return events to the NSWindow.
 - (BOOL)redispatchKeyEvent:(NSEvent*)event;
 
 // Short-circuit to the default -[NSResponder performKeyEquivalent:] which
 // CommandDispatcher calls as part of its -performKeyEquivalent: flow.
 - (BOOL)defaultPerformKeyEquivalent:(NSEvent*)event;
 
+// AppKit will call -[NSUserInterfaceValidations validateUserInterfaceItem:] to
+// validate UI items. Any item whose target is FirstResponder, or nil, will
+// traverse the responder chain looking for a responder that implements the
+// item's selector. Thus NSWindow is usually the last to be checked and will
+// handle any items that are not validated elsewhere in the chain. Implement the
+// following so that menu items with these selectors are validated by
+// CommandDispatchingWindow.
+- (void)commandDispatch:(id)sender;
+- (void)commandDispatchUsingKeyModifiers:(id)sender;
+
 @end
 
 #endif  // UI_BASE_COCOA_COMMAND_DISPATCHER_H_