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_receiver_unittest.cc b/webrtc/modules/video_coding/video_receiver_unittest.cc
index 820ce9a..693fdc6 100644
--- a/webrtc/modules/video_coding/video_receiver_unittest.cc
+++ b/webrtc/modules/video_coding/video_receiver_unittest.cc
@@ -52,7 +52,7 @@
       EXPECT_EQ(0, receiver_->IncomingPacket(payload, 0, *header));
       ++header->header.sequenceNumber;
     }
-    EXPECT_EQ(0, receiver_->Process());
+    receiver_->Process();
     EXPECT_CALL(decoder_, Decode(_, _, _, _, _)).Times(0);
     EXPECT_EQ(VCM_FRAME_NOT_READY, receiver_->Decode(100));
   }
@@ -64,7 +64,7 @@
     EXPECT_EQ(0, receiver_->IncomingPacket(payload, length, *header));
     ++header->header.sequenceNumber;
     EXPECT_CALL(packet_request_callback_, ResendPackets(_, _)).Times(0);
-    EXPECT_EQ(0, receiver_->Process());
+    receiver_->Process();;
     EXPECT_CALL(decoder_, Decode(_, _, _, _, _)).Times(1);
     EXPECT_EQ(0, receiver_->Decode(100));
   }