Replace scoped_ptr with unique_ptr in webrtc/modules/video_coding/

BUG=webrtc:5520

Review URL: https://codereview.webrtc.org/1721353002

Cr-Commit-Position: refs/heads/master@{#11814}
diff --git a/webrtc/modules/video_coding/video_coding_impl.cc b/webrtc/modules/video_coding/video_coding_impl.cc
index 7d6d177..01a7a42 100644
--- a/webrtc/modules/video_coding/video_coding_impl.cc
+++ b/webrtc/modules/video_coding/video_coding_impl.cc
@@ -65,7 +65,7 @@
   }
 
  private:
-  rtc::scoped_ptr<CriticalSectionWrapper> cs_;
+  std::unique_ptr<CriticalSectionWrapper> cs_;
   EncodedImageCallback* callback_ GUARDED_BY(cs_);
 };
 
@@ -283,7 +283,7 @@
   EncodedImageCallbackWrapper post_encode_callback_;
   vcm::VideoSender sender_;
   vcm::VideoReceiver receiver_;
-  rtc::scoped_ptr<EventFactory> own_event_factory_;
+  std::unique_ptr<EventFactory> own_event_factory_;
 };
 }  // namespace