Both DXGI_OUTPUT_DESC and DISPLAY_DEVICE contain the DeviceName, which may be
able to map a DirectX screen id with the GDI screen id.
So this change exports the field from both DirectX and GDI implementations.
BUG=webrtc:7950
Review-Url: https://codereview.webrtc.org/2971393002
Cr-Commit-Position: refs/heads/master@{#19010}