Attach top-left to DesktopFrames generated by DesktopCapturer implementations

This change attaches top-left to the DesktopFrames generated by DesktopCapturer
implementations. Some implementations won't need to attach the top-left because
of the platform specification, e.g. coordinates in X11 always starts from
(0, 0), and we support only one screen.

After this change, we can use the new MouseCursorMonitor::Create() function in

Bug: webrtc:7950
Change-Id: I82c24f4dd9451e32afafb6474f82c32cadcb425c
Reviewed-by: Jamie Walch <>
Commit-Queue: Zijie He <>
Cr-Original-Commit-Position: refs/heads/master@{#19675}
Cr-Mirrored-Commit: 7fdf857d261539b4c03c90ddab1b1256b099dc6a
8 files changed