Cleanup RtcpReceiver tests

update MOCK_METHODs to use new syntax recommended in go/totw/164
Replace fixture with struct of mocks.
Use main method under test (IncomingPacket) directly rather than through fixture helpers

minor cleanup of the RtcReceiver itself:
make IncomingPacket function more friendly to containers,
mark class as final to verify ability to inherit from it is not used and
thus destructor doesn't need to be virtual.

Bug: None
Change-Id: I346e7dc513b1fbe663ebe5858dec7df0520416a7
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/170226
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Markus Handell <handellm@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#30765}

modules/rtp_rtcp/source/rtcp_receiver.cc

@@ -172,14 +172,14 @@ RTCPReceiver::RTCPReceiver(const RtpRtcp::Configuration& config,
 
 RTCPReceiver::~RTCPReceiver() {}
 
-void RTCPReceiver::IncomingPacket(const uint8_t* packet, size_t packet_size) {
-  if (packet_size == 0) {
+void RTCPReceiver::IncomingPacket(rtc::ArrayView<const uint8_t> packet) {
+  if (packet.empty()) {
     RTC_LOG(LS_WARNING) << "Incoming empty RTCP packet";
     return;
   }
 
   PacketInformation packet_information;
-  if (!ParseCompoundPacket(packet, packet + packet_size, &packet_information))
+  if (!ParseCompoundPacket(packet, &packet_information))
     return;
   TriggerCallbacksFromRtcpPacket(packet_information);
 }
@@ -325,18 +325,17 @@ std::vector<ReportBlockData> RTCPReceiver::GetLatestReportBlockData() const {
   return result;
 }
 
-bool RTCPReceiver::ParseCompoundPacket(const uint8_t* packet_begin,
-                                       const uint8_t* packet_end,
+bool RTCPReceiver::ParseCompoundPacket(rtc::ArrayView<const uint8_t> packet,
                                        PacketInformation* packet_information) {
   rtc::CritScope lock(&rtcp_receiver_lock_);
 
   CommonHeader rtcp_block;
-  for (const uint8_t* next_block = packet_begin; next_block != packet_end;
+  for (const uint8_t* next_block = packet.begin(); next_block != packet.end();
        next_block = rtcp_block.NextPacket()) {
-    ptrdiff_t remaining_blocks_size = packet_end - next_block;
+    ptrdiff_t remaining_blocks_size = packet.end() - next_block;
     RTC_DCHECK_GT(remaining_blocks_size, 0);
     if (!rtcp_block.Parse(next_block, remaining_blocks_size)) {
-      if (next_block == packet_begin) {
+      if (next_block == packet.begin()) {
         // Failed to parse 1st header, nothing was extracted from this packet.
         RTC_LOG(LS_WARNING) << "Incoming invalid RTCP packet";
         return false;

modules/rtp_rtcp/source/rtcp_receiver.h

@@ -17,6 +17,7 @@
 #include <string>
 #include <vector>
 
+#include "api/array_view.h"
 #include "modules/rtp_rtcp/include/report_block_data.h"
 #include "modules/rtp_rtcp/include/rtcp_statistics.h"
 #include "modules/rtp_rtcp/include/rtp_rtcp.h"
@@ -37,7 +38,7 @@ class TargetBitrate;
 class TmmbItem;
 }  // namespace rtcp
 
-class RTCPReceiver {
+class RTCPReceiver final {
  public:
   class ModuleRtpRtcp {
    public:
@@ -53,9 +54,12 @@ class RTCPReceiver {
   };
 
   RTCPReceiver(const RtpRtcp::Configuration& config, ModuleRtpRtcp* owner);
-  virtual ~RTCPReceiver();
+  ~RTCPReceiver();
 
-  void IncomingPacket(const uint8_t* packet, size_t packet_size);
+  void IncomingPacket(const uint8_t* packet, size_t packet_size) {
+    IncomingPacket(rtc::MakeArrayView(packet, packet_size));
+  }
+  void IncomingPacket(rtc::ArrayView<const uint8_t> packet);
 
   int64_t LastReceivedReportBlockMs() const;
 
@@ -124,8 +128,7 @@ class RTCPReceiver {
   // RTCP report blocks map mapped by source SSRC.
   using ReportBlockMap = std::map<uint32_t, ReportBlockDataMap>;
 
-  bool ParseCompoundPacket(const uint8_t* packet_begin,
-                           const uint8_t* packet_end,
+  bool ParseCompoundPacket(rtc::ArrayView<const uint8_t> packet,
                            PacketInformation* packet_information);
 
   void TriggerCallbacksFromRtcpPacket(