AsyncPacketSocket::RegisterReceivedPacketCallback

This cl introduce RegisterReceivedPacketCallback and
DeregisterReceivedPacketCallback that will be used to replace AsyncPacketSocket::SignalReadPacket

A "proof of concept" cl is here: https://webrtc-review.googlesource.com/c/src/+/327324

Bug: webrtc:15368
Change-Id: I07e4f564dc8420d78e542991689778d8531225df
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/327325
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Per Kjellander <perkj@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#41164}

rtc_base/async_packet_socket_unittest.cc

diff --git a/rtc_base/async_packet_socket_unittest.cc b/rtc_base/async_packet_socket_unittest.cc
new file mode 100644
index 0000000..6cd4f09
--- /dev/null
+++ b/rtc_base/async_packet_socket_unittest.cc
@@ -0,0 +1,110 @@
+/*
+ *  Copyright 2023 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 "rtc_base/async_packet_socket.h"
+
+#include "rtc_base/third_party/sigslot/sigslot.h"
+#include "test/gmock.h"
+#include "test/gtest.h"
+
+namespace rtc {
+namespace {
+
+using ::testing::MockFunction;
+
+class MockAsyncPacketSocket : public rtc::AsyncPacketSocket {
+ public:
+  ~MockAsyncPacketSocket() = default;
+
+  MOCK_METHOD(SocketAddress, GetLocalAddress, (), (const, override));
+  MOCK_METHOD(SocketAddress, GetRemoteAddress, (), (const, override));
+  MOCK_METHOD(int,
+              Send,
+              (const void* pv, size_t cb, const rtc::PacketOptions& options),
+              (override));
+
+  MOCK_METHOD(int,
+              SendTo,
+              (const void* pv,
+               size_t cb,
+               const SocketAddress& addr,
+               const rtc::PacketOptions& options),
+              (override));
+  MOCK_METHOD(int, Close, (), (override));
+  MOCK_METHOD(State, GetState, (), (const, override));
+  MOCK_METHOD(int,
+              GetOption,
+              (rtc::Socket::Option opt, int* value),
+              (override));
+  MOCK_METHOD(int, SetOption, (rtc::Socket::Option opt, int value), (override));
+  MOCK_METHOD(int, GetError, (), (const, override));
+  MOCK_METHOD(void, SetError, (int error), (override));
+
+  void NotifyPacketReceived() {
+    char data[1] = {'a'};
+    AsyncPacketSocket::NotifyPacketReceived(this, data, 1, SocketAddress(), -1);
+  }
+};
+
+TEST(AsyncPacketSocket, RegisteredCallbackReceivePacketsFromNotify) {
+  MockAsyncPacketSocket mock_socket;
+  MockFunction<void(AsyncPacketSocket*, const rtc::ReceivedPacket&)>
+      received_packet;
+
+  EXPECT_CALL(received_packet, Call);
+  mock_socket.RegisterReceivedPacketCallback(received_packet.AsStdFunction());
+  mock_socket.NotifyPacketReceived();
+}
+
+TEST(AsyncPacketSocket, RegisteredCallbackReceivePacketsFromSignalReadPacket) {
+  MockAsyncPacketSocket mock_socket;
+  MockFunction<void(AsyncPacketSocket*, const rtc::ReceivedPacket&)>
+      received_packet;
+
+  EXPECT_CALL(received_packet, Call);
+  mock_socket.RegisterReceivedPacketCallback(received_packet.AsStdFunction());
+  char data[1] = {'a'};
+  mock_socket.SignalReadPacket(&mock_socket, data, 1, SocketAddress(), -1);
+}
+
+TEST(AsyncPacketSocket, SignalReadPacketTriggeredByNotifyPacketReceived) {
+  class SigslotPacketReceiver : public sigslot::has_slots<> {
+   public:
+    explicit SigslotPacketReceiver(rtc::AsyncPacketSocket& socket) {
+      socket.SignalReadPacket.connect(this,
+                                      &SigslotPacketReceiver::OnPacketReceived);
+    }
+
+    bool packet_received() const { return packet_received_; }
+
+   private:
+    void OnPacketReceived(AsyncPacketSocket*,
+                          const char*,
+                          size_t,
+                          const SocketAddress&,
+                          // TODO(bugs.webrtc.org/9584): Change to passing the
+                          // int64_t timestamp by value.
+                          const int64_t&) {
+      packet_received_ = true;
+    }
+
+    bool packet_received_ = false;
+  };
+
+  MockAsyncPacketSocket mock_socket;
+  SigslotPacketReceiver receiver(mock_socket);
+  ASSERT_FALSE(receiver.packet_received());
+
+  mock_socket.NotifyPacketReceived();
+  EXPECT_TRUE(receiver.packet_received());
+}
+
+}  // namespace
+}  // namespace rtc