commit 8bc9326a0bc6bb2f07fbb1ef60dae1d8cddd2b4a
author zijiehe <zijiehe@chromium.org> Tue Nov 15 02:20:33 2016
committer Commit bot <commit-bot@chromium.org> Tue Nov 15 02:20:41 2016
tree c5da521052a6340e49990039da2b08adcb04929b
parent 69a0e3edea3d61f665520b930920f8a9b2078e41

DirectX capturer flickers on the second monitor

In DxgiOutputDuplicator, we need to convert between a monitor based coordinate
and a entire screen based coordinate. i.e. Copying an updated area from a
monitor (an output in DirectX API) to the entire screen frame (DesktopFrame).
But DxgiOutputDuplicator always assumes the coordinate is based on screen frame.
So we only need to convert a rectange in updated_region to monitor based
coordinate when copying data from texture_. But in last_frame_, the data are
always based on screen coordinate.

So fixes are both required in line 167 and line 180. In the previous one, we do
not need to convert the DesktopRect, which is already screen based, into screen
based coordinate. In the late one, we do not need to convert the DesktopRect at
all. So after these two changes, DxgiOutputDuplicator::TargetRect() function can
be removed.

Flickers of DirectX capturer can happen on any devices, but a virtual machine
can easily reproduce it. While on a regular high performance machine, it's
harder, but not totally impossible, to reproduce the issue.

BUG=314516

Review-Url: https://codereview.webrtc.org/2495143002
Cr-Commit-Position: refs/heads/master@{#15075}