GitLab

Muting:
* There is an AudioSessionMuter class which manages muting for a group.
* InputStreamBroker has one in case source should be muted.
* ForwardingFactory also has one if webcontents should be muted.

Bug: 824019
Change-Id: I41c26e8de38912f9dac1409ff9dba86cd43631ea
Reviewed-on: https://chromium-review.googlesource.com/1046052
Commit-Queue: Olga Sharonova <olka@chromium.org>
Reviewed-by: Max Morin <maxmorin@chromium.org>
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Reviewed-by: Yuri Wiitala <miu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558671}