Revert of Create RtcpDemuxer

webrtc/call/rtp_rtcp_demuxer_helper.h

-/*
- *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#ifndef WEBRTC_CALL_RTP_RTCP_DEMUXER_HELPER_H_
-#define WEBRTC_CALL_RTP_RTCP_DEMUXER_HELPER_H_
-
-#include <algorithm>
-#include <map>
-#include <utility>
-
-#include "webrtc/base/array_view.h"
-#include "webrtc/base/basictypes.h"
-#include "webrtc/base/optional.h"
-
-namespace webrtc {
-
-template <typename Container>
-bool MultimapAssociationExists(const Container& multimap,
-                               const typename Container::key_type& key,
-                               const typename Container::mapped_type& val) {
-  auto it_range = multimap.equal_range(key);
-  using Reference = typename Container::const_reference;
-  return std::any_of(it_range.first, it_range.second,
-                     [val](Reference elem) { return elem.second == val; });
-}
-
-template <typename Container, typename Value>
-size_t RemoveFromMultimapByValue(Container* multimap, const Value& value) {
-  size_t count = 0;
-  for (auto it = multimap->begin(); it != multimap->end();) {
-    if (it->second == value) {
-      it = multimap->erase(it);
-      ++count;
-    } else {
-      ++it;
-    }
-  }
-  return count;
-}
-
-template <typename Container, typename Key>
-bool ContainerHasKey(const Container& c, const Key& k) {
-  return std::find(c.cbegin(), c.cend(), k) != c.cend();
-}
-
-template <typename Container>
-bool MultimapHasValue(const Container& c,
-                      const typename Container::mapped_type& v) {
-  auto predicate = [v](const typename Container::value_type& it) {
-    return it.second == v;
-  };
-  return std::any_of(c.cbegin(), c.cend(), predicate);
-}
-
-rtc::Optional<uint32_t> ParseRtcpPacketSenderSsrc(
-    rtc::ArrayView<const uint8_t> packet);
-
-}  // namespace webrtc
-
-#endif  // WEBRTC_CALL_RTP_RTCP_DEMUXER_HELPER_H_