Reland of Add experimental simulcast screen content mode

The original CL was reverted because of a bug discovered by the
chromium bots. Description of that CL:

> Review-Url: https://codereview.webrtc.org/2636443002
> Cr-Commit-Position: refs/heads/master@{#16135}
> Committed: https://chromium.googlesource.com/external/webrtc/+/a28e971e3bc8a06f366f0ef82cc7168b05a83b59

The first patch set of this CL is the same as r16135.
Subsequence patch sets are the fixes applied.
Some new test cases have been added, which reveal a few more bugs that
have also been fixed.

BUG=webrtc:4172

Review-Url: https://codereview.webrtc.org/2641133002
Cr-Commit-Position: refs/heads/master@{#16299}
12 files changed
tree: a321a86b4c92d37e7047b9949cfbaa7835c3d30a
  1. build_overrides/
  2. data/
  3. infra/
  4. ios/
  5. resources/
  6. tools-webrtc/
  7. webrtc/
  8. .clang-format
  9. .git-blame-ignore-revs
  10. .gitignore
  11. .gn
  12. AUTHORS
  13. BUILD.gn
  14. check_root_dir.py
  15. cleanup_links.py
  16. codereview.settings
  17. DEPS
  18. LICENSE
  19. license_template.txt
  20. LICENSE_THIRD_PARTY
  21. OWNERS
  22. PATENTS
  23. PRESUBMIT.py
  24. pylintrc
  25. README.md
  26. WATCHLISTS
README.md

WebRTC is a free, open software project that provides browsers and mobile applications with Real-Time Communications (RTC) capabilities via simple APIs. The WebRTC components have been optimized to best serve this purpose.

Our mission: To enable rich, high-quality RTC applications to be developed for the browser, mobile platforms, and IoT devices, and allow them all to communicate via a common set of protocols.

The WebRTC initiative is a project supported by Google, Mozilla and Opera, amongst others. This page is maintained by the Google Chrome team.

Development

See http://www.webrtc.org/native-code/development for instructions on how to get started developing with the native code.

More info