Is there any API Document Browser like Dash on Ubuntu?

You might want to check out Zeal. I just started implementing it this weekend. It's intended to be a documentation browser like Dash, working on Linux.

Here is a screenshot:

Perhaps devdocs.io would be an option. It is also available as app extension for google chrome.

devhelp may help you

Devhelp is an API documentation browser for GTK+ and GNOME. It works natively with gtk-doc (the API reference framework developed for GTK+ and used throughout GNOME for API documentation). If you use gtk-doc with your project, you can use Devhelp to browse the documentation.

website

screenshot