zijiehe 41e3d9ff3b Add DesktopCapturerId and attach it to DesktopFrame
This change adds a DesktopCapturerId namespace, and attaches an int to each
DesktopFrame. ScreenCapturerWinGdi and ScreenCapturerWinDirectx now actively set
this field to differentiate themselves.

BUG=679523, 650926

Review-Url: https://codereview.webrtc.org/2759493002
Cr-Commit-Position: refs/heads/master@{#17329}
2017-03-21 19:41:18 +00:00
..
2016-11-16 19:11:38 +00:00