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}
diff --git a/webrtc/modules/video_coding/video_coding_impl.h b/webrtc/modules/video_coding/video_coding_impl.h
index 581ab0e..dc766b1 100644
--- a/webrtc/modules/video_coding/video_coding_impl.h
+++ b/webrtc/modules/video_coding/video_coding_impl.h
@@ -93,7 +93,7 @@
   bool VideoSuspended() const;
 
   int64_t TimeUntilNextProcess();
-  int32_t Process();
+  void Process();
 
  private:
   void SetEncoderParameters(EncoderParameters params)
@@ -172,7 +172,7 @@
   int32_t SetVideoProtection(VCMVideoProtection videoProtection, bool enable);
 
   int64_t TimeUntilNextProcess();
-  int32_t Process();
+  void Process();
 
   void RegisterPreDecodeImageCallback(EncodedImageCallback* observer);
   void TriggerDecoderShutdown();