Revert of Remove ignored return code from modules. (patchset #3 id:40001 of https://codereview.webrtc.org/1703833002/ )

Reason for revert:
Breaks Chromium.

Original issue's description:
> 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
>
> Committed: f14c47a58c

TBR=tommi@webrtc.org,pbos@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.webrtc.org/1736663004

Cr-Commit-Position: refs/heads/master@{#11761}

webrtc/modules/audio_device/audio_device_impl.cc

@@ -427,7 +427,7 @@ int64_t AudioDeviceModuleImpl::TimeUntilNextProcess()
 //  new reports exists.
 // ----------------------------------------------------------------------------
 
-void AudioDeviceModuleImpl::Process()
+int32_t AudioDeviceModuleImpl::Process()
 {
 
     _lastProcessTime = TickTime::MillisecondTimestamp();
@@ -479,6 +479,8 @@ void AudioDeviceModuleImpl::Process()
         }
         _ptrAudioDevice->ClearRecordingError();
     }
+
+    return 0;
 }
 
 // ============================================================================