Use PostTask instead of MessageHandler for cert generation.
Use PostTask instead of MessageHandler for cert generation.

Bug: webrtc:11908
Change-Id: Iaad4f0e398980eeae77187a32dfade0c26eb4cc8
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/184061
Reviewed-by: Henrik Boström <106ab6647ddadbf38d6259e9d5ec4de77fa52c00@webrtc.org>
Commit-Queue: Tommi <74a97831ec830b6e3846c6faa50560947ae01c68@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#32098}

TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc