Objective C API to read and set RtpParameters

This change adds the Objective C API functions to get and set RtpSender's
RtpParameters, which allows setting bitrate limits for audio and video and
turning off RtpSenders to pre-initialize the encoder.

This CL adds only the smallest set of methods required to support bitrate
limiting - there is no way to create an RtpSender, for example, or to set
its track. The only supported functionality is this:
 	RTCPeerConnection.senders - a read-only property returning the array
	  of all RTCRtpSenders for the connection.
        RTCRtpSender.parameters - a read-only property returning the current
    	  parameters
	RTCRtpSender.setParameters: - a method to change the parameters.
	RTCRtpSender.track - a read-only property returning the
	  RTCMediaStreamTrack corresponding to the sender. It is necessary
	  to be able to identify RTCRtpSenders for video and audio. The
	  track object is of the base RTCMediaStreamTrack type, not of the
          specific subclass for audio and video - just like it is in the
	  Java API.

BUG=

Review URL: https://codereview.webrtc.org/1854393002

Cr-Commit-Position: refs/heads/master@{#12297}
15 files changed
tree: 831383ab6ec9e90ba42140cddc4953e5db68e96b
  1. build_overrides/
  2. chromium/
  3. data/
  4. infra/
  5. resources/
  6. talk/
  7. third_party/
  8. tools/
  9. webrtc/
  10. .clang-format
  11. .gitignore
  12. .gn
  13. all.gyp
  14. AUTHORS
  15. BUILD.gn
  16. check_root_dir.py
  17. codereview.settings
  18. COPYING
  19. DEPS
  20. LICENSE
  21. license_template.txt
  22. LICENSE_THIRD_PARTY
  23. OWNERS
  24. PATENTS
  25. PRESUBMIT.py
  26. pylintrc
  27. README.md
  28. setup_links.py
  29. sync_chromium.py
  30. 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