Remove dependency on AsyncInvoker in SctpTransport

Bug: webrtc:11988
Change-Id: I996aa220a00b61fb5080803bffe7a37c6b90aaec
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/193866
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Tommi <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32645}

media/BUILD.gn

@@ -408,6 +408,8 @@ rtc_library("rtc_data") {
     "../rtc_base",
     "../rtc_base:rtc_base_approved",
     "../rtc_base/synchronization:mutex",
+    "../rtc_base/task_utils:pending_task_safety_flag",
+    "../rtc_base/task_utils:to_queued_task",
     "../rtc_base/third_party/sigslot",
     "../system_wrappers",
   ]

media/sctp/sctp_transport.cc

@@ -46,6 +46,7 @@ constexpr int kSctpSuccessReturn = 1;
 #include "rtc_base/numerics/safe_conversions.h"
 #include "rtc_base/string_utils.h"
 #include "rtc_base/synchronization/mutex.h"
+#include "rtc_base/task_utils/to_queued_task.h"
 #include "rtc_base/thread_annotations.h"
 #include "rtc_base/thread_checker.h"
 #include "rtc_base/trace_event.h"
@@ -386,11 +387,12 @@ class SctpTransport::UsrSctpWrapper {
     VerboseLogPacket(data, length, SCTP_DUMP_OUTBOUND);
     // Note: We have to copy the data; the caller will delete it.
     rtc::CopyOnWriteBuffer buf(reinterpret_cast<uint8_t*>(data), length);
-    // TODO(deadbeef): Why do we need an AsyncInvoke here? We're already on the
-    // right thread and don't need to unwind the stack.
-    transport->invoker_.AsyncInvoke<void>(
-        RTC_FROM_HERE, transport->network_thread_,
-        rtc::Bind(&SctpTransport::OnPacketFromSctpToNetwork, transport, buf));
+
+    transport->network_thread_->PostTask(ToQueuedTask(
+        transport->task_safety_, [transport, buf = std::move(buf)]() {
+          transport->OnPacketFromSctpToNetwork(buf);
+        }));
+
     return 0;
   }
 
@@ -497,6 +499,7 @@ SctpTransport::SctpTransport(rtc::Thread* network_thread,
 }
 
 SctpTransport::~SctpTransport() {
+  RTC_DCHECK_RUN_ON(network_thread_);
   // Close abruptly; no reset procedure.
   CloseSctpSocket();
   // It's not strictly necessary to reset these fields to nullptr,
@@ -1165,9 +1168,10 @@ int SctpTransport::OnDataOrNotificationFromSctp(void* data,
     // Copy and dispatch asynchronously
     rtc::CopyOnWriteBuffer notification(reinterpret_cast<uint8_t*>(data),
                                         length);
-    invoker_.AsyncInvoke<void>(
-        RTC_FROM_HERE, network_thread_,
-        rtc::Bind(&SctpTransport::OnNotificationFromSctp, this, notification));
+    network_thread_->PostTask(ToQueuedTask(
+        task_safety_, [this, notification = std::move(notification)]() {
+          OnNotificationFromSctp(notification);
+        }));
     return kSctpSuccessReturn;
   }
 
@@ -1239,10 +1243,11 @@ int SctpTransport::OnDataOrNotificationFromSctp(void* data,
   // Dispatch the complete message.
   // The ownership of the packet transfers to |invoker_|. Using
   // CopyOnWriteBuffer is the most convenient way to do this.
-  invoker_.AsyncInvoke<void>(
-      RTC_FROM_HERE, network_thread_,
-      rtc::Bind(&SctpTransport::OnDataFromSctpToTransport, this, params,
-                partial_incoming_message_));
+  network_thread_->PostTask(webrtc::ToQueuedTask(
+      task_safety_, [this, params = std::move(params),
+                     message = partial_incoming_message_]() {
+        OnDataFromSctpToTransport(params, message);
+      }));
 
   // Reset the message buffer
   partial_incoming_message_.Clear();

media/sctp/sctp_transport.h

@@ -22,10 +22,10 @@
 
 #include "absl/types/optional.h"
 #include "api/transport/sctp_transport_factory_interface.h"
-#include "rtc_base/async_invoker.h"
 #include "rtc_base/buffer.h"
 #include "rtc_base/constructor_magic.h"
 #include "rtc_base/copy_on_write_buffer.h"
+#include "rtc_base/task_utils/pending_task_safety_flag.h"
 #include "rtc_base/third_party/sigslot/sigslot.h"
 #include "rtc_base/thread.h"
 // For SendDataParams/ReceiveDataParams.
@@ -199,7 +199,7 @@ class SctpTransport : public SctpTransportInternal,
   // outgoing data to the network interface.
   rtc::Thread* network_thread_;
   // Helps pass inbound/outbound packets asynchronously to the network thread.
-  rtc::AsyncInvoker invoker_;
+  webrtc::ScopedTaskSafety task_safety_;
   // Underlying DTLS transport.
   rtc::PacketTransportInternal* transport_ = nullptr;
 

media/sctp/sctp_transport_reliability_unittest.cc

@@ -14,6 +14,7 @@
 #include <string>
 
 #include "media/sctp/sctp_transport_internal.h"
+#include "rtc_base/async_invoker.h"
 #include "rtc_base/copy_on_write_buffer.h"
 #include "rtc_base/gunit.h"
 #include "rtc_base/logging.h"

pc/sctp_transport.cc

@@ -13,6 +13,8 @@
 #include <algorithm>
 #include <utility>
 
+#include "rtc_base/bind.h"
+
 namespace webrtc {
 
 SctpTransport::SctpTransport(