[MacViews] Use ChromeCommandDispatcherDelegate to handle keyboard shortcuts.

ui/views/cocoa/native_widget_mac_nswindow.h

Index: ui/views/cocoa/native_widget_mac_nswindow.h
diff --git a/ui/views/cocoa/native_widget_mac_nswindow.h b/ui/views/cocoa/native_widget_mac_nswindow.h
index 8886654763e82f5d8ce9c50a234467148a9786f0..527596c40099cd2504ff16ad0b7b5ec589562aa0 100644
--- a/ui/views/cocoa/native_widget_mac_nswindow.h
+++ b/ui/views/cocoa/native_widget_mac_nswindow.h
@@ -17,6 +17,10 @@ VIEWS_EXPORT
  @private
   base::scoped_nsobject<CommandDispatcher> commandDispatcher_;
 }
+
+// Set a CommandDispatcherDelegate, i.e. to implement key event handling.
+- (void)setCommandDispatcherDelegate:(id<CommandDispatcherDelegate>)delegate;
+
 @end
 
 #endif  // UI_VIEWS_COCOA_NATIVE_WIDGET_MAC_NSWINDOW_H_