[Mac] Move UI item validation to UserInterfaceItemCommandHandler.

ui/views/cocoa/native_widget_mac_nswindow.mm

Index: ui/views/cocoa/native_widget_mac_nswindow.mm
diff --git a/ui/views/cocoa/native_widget_mac_nswindow.mm b/ui/views/cocoa/native_widget_mac_nswindow.mm
index 1de283fb956b7dc53d180ed36ec06e1e07d4ae91..3f2eb7ce64c687b69f0be1a58600f102a4ea0bf1 100644
--- a/ui/views/cocoa/native_widget_mac_nswindow.mm
+++ b/ui/views/cocoa/native_widget_mac_nswindow.mm
@@ -25,6 +25,8 @@
   base::scoped_nsobject<CommandDispatcher> commandDispatcher_;
 }
 
+@synthesize commandHandler;

[tapted, 2015/09/04 02:56:24]

With this approach (i.e. assign not retain), I think the handler can easily be
destroyed before the NSWindow.

E.g. BrowserFrameMac can remove the last reference to its handler and destroy
it, but the NSWindow can still be receiving events, leading to UAF in this
class.

I think either this needs to be a scoped_nsobject + retain semantics, or the
commandDispatcher should own it instead.

[jackhou1, 2015/09/04 06:13:59]

Changed to retain.

+
 - (instancetype)initWithContentRect:(NSRect)contentRect
                           styleMask:(NSUInteger)windowStyle
                             backing:(NSBackingStoreType)bufferingType
@@ -168,4 +170,29 @@
   return [super performKeyEquivalent:event];
 }
 
+- (void)commandDispatch:(id)sender {
+  [[self commandHandler] commandDispatch:sender window:self];
+}
+
+- (void)commandDispatchUsingKeyModifiers:(id)sender {
+  [[self commandHandler] commandDispatchUsingKeyModifiers:sender window:self];
+}
+
+// NSWindow overrides (NSUserInterfaceItemValidations implementation)
+
+- (BOOL)validateUserInterfaceItem:(id<NSValidatedUserInterfaceItem>)item {
+  // Since this class implements these selectors, |super| will always say they

[tapted, 2015/09/04 02:56:24]

Then perhaps this logic can move into commandDispatcher and be shared

[jackhou1, 2015/09/04 06:13:59]

Ah, I agree sharing this logic would be good. But we'd need to add
defaultValidateUserInterfaceItem to CommandDispatchingWindow... and I still
don't think CommandDispatcher really needs to be involved.

+  // are enabled. Only use [super] to validate other selectors. If there is no
+  // command handler, defer to AppController.
+  if ([item action] == @selector(commandDispatch:) ||
+      [item action] == @selector(commandDispatchUsingKeyModifiers:)) {
+    return
+        [self commandHandler]
+            ? [[self commandHandler] validateUserInterfaceItem:item window:self]
+            : [[NSApp delegate] validateUserInterfaceItem:item];
+  }
+
+  return [super validateUserInterfaceItem:item];
+}
+
 @end