API description: PeerConnection description
Since we want most users to use the PeerConnection API, this is the
part that we should document.
If we want people to use other APIs, we can add to the file.
Bug: webrtc:12674
Change-Id: Icf14f218cf51c640e6f846f10b49dff84106dc21
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/215066
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Artem Titov <titovartem@webrtc.org>
Reviewed-by: Tommi <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33707}
diff --git a/api/g3doc/index.md b/api/g3doc/index.md
index fe8d9b5..49637d1 100644
--- a/api/g3doc/index.md
+++ b/api/g3doc/index.md
@@ -11,3 +11,41 @@
* Memory management, including webrtc's reference counted objects
* [Thread management](threading_design.md)
+
+## Using WebRTC through the PeerConnection class
+
+The
+[PeerConnectionInterface](https://source.chromium.org/chromium/chromium/src/+/master:third_party/webrtc/api/peer_connection_interface.h?q=webrtc::PeerConnectionInterface)
+class is the recommended way to use the WebRTC library.
+
+It is closely modeled after the Javascript API documented in the [WebRTC
+specification](https://w3c.github.io/webrtc-pc/).
+
+PeerConnections are created using the [PeerConnectionFactoryInterface](https://source.chromium.org/search?q=webrtc::PeerConnectionFactoryInterface).
+
+There are two levels of customization available:
+
+* Pass a PeerConnectionFactoryDependencies object to the function that creates
+ a PeerConnectionFactory. This object defines factories for a lot of internal
+ objects inside the PeerConnection, so that users can override them.
+ All PeerConnections using this interface will have the same options.
+* Pass a PeerConnectionInterface::RTCConfiguration object to the
+ CreatePeerConnectionOrError() function on the
+ PeerConnectionFactoryInterface. These customizations will apply only to a
+ single PeerConnection.
+
+Most functions on the PeerConnection interface are asynchronous, and take a
+callback that is executed when the function is finished. The callbacks are
+mostly called on the thread that is passed as the "signaling thread" field of
+the PeerConnectionFactoryDependencies, or the thread that called
+PeerConnectionFactory::CreatePeerConnectionOrError() if no thread is given.
+
+See each class' module documentation for details.
+
+## Using WebRTC components without the PeerConnection class
+
+This needs to be done carefully, and in consultation with the WebRTC team. There
+are non-obvious dependencies between many of the components.
+
+
+
