Called to execute a Chrome command triggered via menu selection or keyboard shortcut. Values for |command_id| can be found in the cef_command_ids.h file. |disposition| provides information about the intended command target. Return true (1) if the command was handled or false (0) for the default implementation. For context menu commands this will be called after cef_context_menu_handler_t::OnContextMenuCommand. Only used with the Chrome runtime.