[Mac] Move UI item validation to UserInterfaceItemCommandHandler.

ui/base/cocoa/command_dispatcher.h

Index: ui/base/cocoa/command_dispatcher.h
diff --git a/ui/base/cocoa/command_dispatcher.h b/ui/base/cocoa/command_dispatcher.h
index e6171390d12a37fb40e4444bbbfa34ce938167e6..2e565767c8a3a8af413ad3666611fa95a9479fb2 100644
--- a/ui/base/cocoa/command_dispatcher.h
+++ b/ui/base/cocoa/command_dispatcher.h
@@ -11,6 +11,7 @@
 
 @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
@@ -78,7 +79,9 @@
 
 // The set of methods an NSWindow subclass needs to implement to use
 // CommandDispatcher.
-@protocol CommandDispatchingWindow
+@protocol CommandDispatchingWindow<NSUserInterfaceValidations>

[tapted, 2015/08/27 07:24:42]

does the window need to implement this (i.e. is the dispatcher relying on this?
it doesn't seem to, and it uses NSWidnow for storage anyway

[jackhou1, 2015/09/03 01:12:49]

Yeah it's not necessary to require this.

+
+@property(assign, nonatomic) id<UserInterfaceItemCommandHandler> commandHandler;

[tapted, 2015/08/27 07:24:42]

Could we just force the owner to implement this?

[jackhou1, 2015/09/03 01:12:49]

Yeah, this is only used to set it on NativeWidgetMacNSWindow, moved to there.

 
 // This can be implemented with -[CommandDispatcher redispatchKeyEvent:]. It's
 // so that callers can simply return events to the NSWindow.
@@ -88,6 +91,39 @@
 // 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;

[tapted, 2015/08/28 05:04:02]

What's calling these?

What happens if we refactor those call sites to call methods on the
CommandDispatcher directly?

CommandDispatchingWindow then just needs a method to return the
CommandDisptcher*.


(I think I may have given the opposite advice for redispatchKeyEvent, but now
there's multiple functions it looks a bit clumsy -- i.e. with that change,
callers of [[foo window] redispatchKeyEvent:..] could be updated to instead do 
[[[foo window] commandDispatcher] redispatchKeyEvent:..])

[jackhou1, 2015/09/03 01:12:49]

These are hard coded in the nibs. I.e. a button might have
{target=FirstResponder, selector=commandDispatch:}, so it'll go up the chain
looking for something that responds to the selector.

+- (void)commandDispatchUsingKeyModifiers:(id)sender;
+
+@end
+
+// Used by CommandDispatchingWindow to implement UI item validation.
+@protocol UserInterfaceItemCommandHandler
+
+// Called by CommandDispatchingWindow to validate menu and toolbar items. All
+// the items we care about have been set with the -commandDispatch or
+// -commandDispatchUsingKeyModifiers selectors and a target of FirstResponder in
+// IB. If it's not one of those, it should be handled elsewhere in the responder
+// chain.
+- (BOOL)validateUserInterfaceItem:(id<NSValidatedUserInterfaceItem>)item
+                           window:(NSWindow*)window;
+
+// Called by CommandDispatchingWindow to execute commands. This assumes that the
+// command is supported and doesn't check, otherwise it would have been disabled
+// in the UI in validateUserInterfaceItem:.
+- (void)commandDispatch:(id)sender window:(NSWindow*)window;
+
+// Same as |-commandDispatch:|, but executes commands using a disposition
+// determined by the key flags. If the window is in the background and the
+// command key is down, ignore the command key, but process any other modifiers.
+- (void)commandDispatchUsingKeyModifiers:(id)sender window:(NSWindow*)window;
+
 @end
 
 #endif  // UI_BASE_COCOA_COMMAND_DISPATCHER_H_