Remove ignored return code from modules.

ModuleProcessImpl doesn't act on return codes and having them around is
confusing (it's unclear what an error return code here would do even).

BUG=
R=tommi@webrtc.org

Review URL: https://codereview.webrtc.org/1703833002 .

Cr-Original-Commit-Position: refs/heads/master@{#11747}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: f14c47a58cb2a333cb9b11aef593f0e632fdb28a
66 files changed