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-Commit-Position: refs/heads/master@{#11747}

webrtc/modules/video_coding/test/vcm_payload_sink_factory.cc

@@ -74,9 +74,7 @@ class VcmPayloadSinkFactory::VcmPayloadSink : public PayloadSinkInterface,
 
   bool Process() {
     if (vcm_->TimeUntilNextProcess() <= 0) {
-      if (vcm_->Process() < 0) {
-        return false;
-      }
+      vcm_->Process();
     }
     return true;
   }