Add style guide rules for std::bind and std::function
Add style guide rules for std::bind and std::function

We keep std::bind forbidden just like before, but suggest another
alternative than the Chromium style guide does.

We allow std::function, overriding the Chromium style guide which
forbids it on grounds not really applicable to WebRTC.

Bug: none
Change-Id: Iad07485652064a67020a494466d2b212bad568c0
Notry: true
Reviewed-on: https://webrtc-review.googlesource.com/63028
Reviewed-by: Niels Moller <0057859e47d61d90529d0f66d9ef692cefedb46a@webrtc.org>
Commit-Queue: Karl Wiberg <2c708eb0a58047bf403399f50b3da33ffd2dd444@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#22553}
TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc