Convert LocalMuter and StreamFactory to new Mojo types

This CL converts LocalMuterAssociatedRequest and StreamFactoryPtr
in content to the new Mojo types.

Bug: 955171
Change-Id: I08356dd12197b7db14730f7045da0b1742e69804
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1786891
Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Reviewed-by: Olga Sharonova <olka@chromium.org>
Commit-Queue: Miyoung Shin <myid.shin@igalia.com>
Cr-Commit-Position: refs/heads/master@{#695418}