Data for each device should be placed in a separate directory, with "device.json" file describing the device:
- "type" should be one of the "phone", "tablet", "notebook", "desktop", "unknown";
- "capabilities" should listen enabled capabilities for the device (currently supported: "mobile", "touch");
- "screen" describes the physical device screen size and dpr in horizontal and vertical orientations;
- "outline" provides an image to draw around the screen;
- "modes" represent different browser states on the screen (e.g. with/without on-screen keyboard);
- "page-rect" is the rect relative to the "screen" size (see above), where web page is displayed; this rect will be emulated;
- all sizes in should be in device independent pixels;
- all "title" values should be user-readable.

File "devices.json" should be generated using "generate_devices_list.py" script.