New layout file content_xxxxx.xml in Android Studio 1.4

Question

I just updated Android Studio from 1.3 to 1.4, and there are some new features that I don't quite understand. When creating a new one Blank Activity, two .xml layout files are added. The name of my activity PaymentActivity, so I get content_payment.xmland activity_payment.xml. This file content_payment.xmlcontains nothing but RelativeLayoutthat has this in it:

 tools:showIn="@layout/activity_payment">

What is this new layout?

Answer 1

Activity (Blank Activity, Scrolling Activity ..), . AND content_xxx.

content_xxx, .

(- Blank Activity), , . content_xxx.

, , , .

Answer 2

activity_main.xml content_main.xml FABs ( ).

, , , .. , Google .