Move ScreenCapturer 'real' tests out of screen_capturer_unittest.cc.
This is a trivial change, I just cutted and pasted part of the code in
screen_capturer_unittest.cc to screen_capturer_integration_test.cc, removed
DISABLED_ prefixes, and updated build file.
BUG=webrtc:6366
Review-Url: https://codereview.webrtc.org/2444583002
Cr-Original-Commit-Position: refs/heads/master@{#14806}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 6be0a657c563acfb3f9b2502c4453d7ba46ef0d1
6 files changed
