Move RtpFrameReferenceFinder out of video_coding namespace.

Namespace used because of copy-pasting an old pattern, should never have been used in the first place. Removing it now to make followup refactoring prettier.

Bug: webrtc:12579
Change-Id: I00a80958401cfa368769dc0a1d8bbdd76aaa4ef5
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/212603
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Philip Eliasson <philipel@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33536}

video/rtp_video_stream_receiver2.cc

diff --git a/video/rtp_video_stream_receiver2.cc b/video/rtp_video_stream_receiver2.cc
index 4893d1a..8ea1bc7 100644
--- a/video/rtp_video_stream_receiver2.cc
+++ b/video/rtp_video_stream_receiver2.cc
@@ -213,7 +213,7 @@
     ProcessThread* process_thread,
     NackSender* nack_sender,
     KeyFrameRequestSender* keyframe_request_sender,
-    video_coding::OnCompleteFrameCallback* complete_frame_callback,
+    OnCompleteFrameCallback* complete_frame_callback,
     rtc::scoped_refptr<FrameDecryptorInterface> frame_decryptor,
     rtc::scoped_refptr<FrameTransformerInterface> frame_transformer)
     : clock_(clock),
@@ -294,8 +294,7 @@
                                                      &rtcp_feedback_buffer_);
   }
 
-  reference_finder_ =
-      std::make_unique<video_coding::RtpFrameReferenceFinder>(this);
+  reference_finder_ = std::make_unique<RtpFrameReferenceFinder>(this);
 
   // Only construct the encrypted receiver if frame encryption is enabled.
   if (config_.crypto_options.sframe.require_frame_encryption) {
@@ -832,10 +831,9 @@
         // to overlap with old picture ids. To ensure that doesn't happen we
         // start from the |last_completed_picture_id_| and add an offset in case
         // of reordering.
-        reference_finder_ =
-            std::make_unique<video_coding::RtpFrameReferenceFinder>(
-                this, last_completed_picture_id_ +
-                          std::numeric_limits<uint16_t>::max());
+        reference_finder_ = std::make_unique<RtpFrameReferenceFinder>(
+            this,
+            last_completed_picture_id_ + std::numeric_limits<uint16_t>::max());
         current_codec_ = frame->codec_type();
       } else {
         // Old frame from before the codec switch, discard it.