Make the RtpHeaderParserImpl available to tests and tools only.

There are a few reasons for making this test only:
* The code is only used by tests and utilities.
* The pure interface has only a single implementation so an interface isn't really needed.
  (a followup change could remove it altogether)
* The implementation always incorporates locking regardless of how the class gets used.
  See e.g. previous use in the Packet class.
* The implementation is a layer on top of RtpUtility::RtpHeaderParser which is
  sufficient for most production cases.

Change-Id: Ide6d50567cf8ae5127a2eb04cceeb10cf317ec36
Bug: none
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/150658
Commit-Queue: Tommi <tommi@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29010}

test/rtp_header_parser.cc

@@ -0,0 +1,103 @@
+/*
+ *  Copyright (c) 2013 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.
+ */
+#include "test/rtp_header_parser.h"
+
+#include <memory>
+
+#include "absl/memory/memory.h"
+#include "modules/rtp_rtcp/include/rtp_header_extension_map.h"
+#include "modules/rtp_rtcp/source/rtp_utility.h"
+#include "rtc_base/critical_section.h"
+#include "rtc_base/thread_annotations.h"
+
+namespace webrtc {
+
+class RtpHeaderParserImpl : public RtpHeaderParser {
+ public:
+  RtpHeaderParserImpl();
+  ~RtpHeaderParserImpl() override = default;
+
+  bool Parse(const uint8_t* packet,
+             size_t length,
+             RTPHeader* header) const override;
+
+  bool RegisterRtpHeaderExtension(RTPExtensionType type, uint8_t id) override;
+  bool RegisterRtpHeaderExtension(RtpExtension extension) override;
+
+  bool DeregisterRtpHeaderExtension(RTPExtensionType type) override;
+  bool DeregisterRtpHeaderExtension(RtpExtension extension) override;
+
+ private:
+  rtc::CriticalSection critical_section_;
+  RtpHeaderExtensionMap rtp_header_extension_map_
+      RTC_GUARDED_BY(critical_section_);
+};
+
+std::unique_ptr<RtpHeaderParser> RtpHeaderParser::CreateForTest() {
+  return absl::make_unique<RtpHeaderParserImpl>();
+}
+
+RtpHeaderParserImpl::RtpHeaderParserImpl() {}
+
+bool RtpHeaderParser::IsRtcp(const uint8_t* packet, size_t length) {
+  RtpUtility::RtpHeaderParser rtp_parser(packet, length);
+  return rtp_parser.RTCP();
+}
+
+absl::optional<uint32_t> RtpHeaderParser::GetSsrc(const uint8_t* packet,
+                                                  size_t length) {
+  RtpUtility::RtpHeaderParser rtp_parser(packet, length);
+  RTPHeader header;
+  if (rtp_parser.Parse(&header, nullptr)) {
+    return header.ssrc;
+  }
+  return absl::nullopt;
+}
+
+bool RtpHeaderParserImpl::Parse(const uint8_t* packet,
+                                size_t length,
+                                RTPHeader* header) const {
+  RtpUtility::RtpHeaderParser rtp_parser(packet, length);
+  *header = RTPHeader();
+
+  RtpHeaderExtensionMap map;
+  {
+    rtc::CritScope cs(&critical_section_);
+    map = rtp_header_extension_map_;
+  }
+
+  const bool valid_rtpheader = rtp_parser.Parse(header, &map);
+  if (!valid_rtpheader) {
+    return false;
+  }
+  return true;
+}
+bool RtpHeaderParserImpl::RegisterRtpHeaderExtension(RtpExtension extension) {
+  rtc::CritScope cs(&critical_section_);
+  return rtp_header_extension_map_.RegisterByUri(extension.id, extension.uri);
+}
+
+bool RtpHeaderParserImpl::RegisterRtpHeaderExtension(RTPExtensionType type,
+                                                     uint8_t id) {
+  rtc::CritScope cs(&critical_section_);
+  return rtp_header_extension_map_.RegisterByType(id, type);
+}
+
+bool RtpHeaderParserImpl::DeregisterRtpHeaderExtension(RtpExtension extension) {
+  rtc::CritScope cs(&critical_section_);
+  return rtp_header_extension_map_.Deregister(
+      rtp_header_extension_map_.GetType(extension.id));
+}
+
+bool RtpHeaderParserImpl::DeregisterRtpHeaderExtension(RTPExtensionType type) {
+  rtc::CritScope cs(&critical_section_);
+  return rtp_header_extension_map_.Deregister(type) == 0;
+}
+}  // namespace webrtc