Change PeerConnection error codes
Change PeerConnection error codes

Change error code for "state mismatch" to "State error",
and also change some parameter errors to "Illegal parameter".

Bug: chromium:819629
Change-Id: I9347d4161344b4ff2bcb58ad82fa6d533cd476fb
Reviewed-on: https://webrtc-review.googlesource.com/69815
Reviewed-by: Benjamin Wright <d97cb5a683a42395ddbd3524ae4315b2c4b93d14@webrtc.org>
Reviewed-by: Henrik Boström <106ab6647ddadbf38d6259e9d5ec4de77fa52c00@webrtc.org>
Commit-Queue: Harald Alvestrand <ce816cd73d80f958d82de1df356058c2d2bca378@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#22924}
TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc