Atmel stated in their website:
Atmel Studio 7 features seamless one-click import of projects created in the Arduino development environment. Your sketch, including any libraries it references, will be imported into Studio 7 as a C++ project. Once imported, you can leverage the full capabilities of Studio 7 to fine-tune and debug your design. Atmel Studio 7 fully supports the powerful embedded debugger on the Arduino Zero board. For other Arduino boards, shield-adapters that expose debug connectors are available, or switch to one of the many available Xplained-Mini/PRO boards to fully leverage the Atmel HW eco-system. Regardless of what you choose, you will surely make something amazing.
I wonder how they do it? Is it just a plug-in meaning that we still have to install Arduino software? Or do they have their own compiler and debugger?