Reland "Add RTC_EXPORT macro to export WebRTC symbols."

This is a reland of 55daf1aef65218a97eff88999e5190a2f2f6b72e.

In order to avoid problems on case insensitive file systems this CL
moves rtc_export.h to rtc_base/system (avoiding problems with build/).

Diff: https://webrtc-review.googlesource.com/c/src/+/100804/1..2.

Original change's description:
> Add RTC_EXPORT macro to export WebRTC symbols.
>
> This CL introduces the utility macro RTC_EXPORT which will let WebRTC
> developers decide which symbols are supposed to be exported/imported
> and which ones are private.
>
> RTC_EXPORT will only export/import symbols in a component build, more
> info: https://cs.chromium.org/chromium/src/docs/component_build.md.
> During a component build, the macro COMPONENT_BUILD will be globally
> defined in a consistent fashion so it is safe to rely on it to
> understand how to expand RTC_EXPORT.
> In a non component build, RTC_EXPORT will expand to nothing.
>
> Bug: webrtc:9419
> Change-Id: Ic58162783be7f5883136ade27f324d6d34fdf932
> Reviewed-on: https://webrtc-review.googlesource.com/97960
> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
> Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
> Reviewed-by: Niels Moller <nisse@webrtc.org>
> Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
> Reviewed-by: Yves Gerey <yvesg@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#24757}

Bug: webrtc:9419
Change-Id: Icfedea5fc3416ea1af2185de443fa879fb2dee8b
Reviewed-on: https://webrtc-review.googlesource.com/100804
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24766}
4 files changed
tree: e04c1c736c08dd4b93fb61283442a23d7ab3c788
  1. api/
  2. audio/
  3. build_overrides/
  4. call/
  5. common_audio/
  6. common_video/
  7. data/
  8. examples/
  9. infra/
  10. logging/
  11. media/
  12. modules/
  13. ortc/
  14. p2p/
  15. pc/
  16. resources/
  17. rtc_base/
  18. rtc_tools/
  19. sdk/
  20. stats/
  21. style-guide/
  22. system_wrappers/
  23. test/
  24. tools_webrtc/
  25. video/
  26. .clang-format
  27. .git-blame-ignore-revs
  28. .gitignore
  29. .gn
  30. .vpython
  31. abseil-in-webrtc.md
  32. AUTHORS
  33. BUILD.gn
  34. CODE_OF_CONDUCT.md
  35. codereview.settings
  36. common_types.h
  37. DEPS
  38. LICENSE
  39. license_template.txt
  40. native-api.md
  41. OWNERS
  42. PATENTS
  43. PRESUBMIT.py
  44. presubmit_test.py
  45. presubmit_test_mocks.py
  46. pylintrc
  47. README.chromium
  48. README.md
  49. style-guide.md
  50. WATCHLISTS
  51. webrtc.gni
  52. whitespace.txt
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.

Development

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

Authoritative list of directories that contain the native API header files.

More info