In FakeNetworkManager remove MessageHandlerAutoCleanup dependency.

Post task in a less safer way assuming test won't try to destroy the manager right after starting the updates.

Bug: webrtc:11988
Change-Id: Idf5d001b9c09d8df793112e4ad95690f9660ac3a
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/273961
Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#38007}

rtc_base/fake_network.h

diff --git a/rtc_base/fake_network.h b/rtc_base/fake_network.h
index 4501c9a..d78d8a7 100644
--- a/rtc_base/fake_network.h
+++ b/rtc_base/fake_network.h
@@ -17,9 +17,7 @@
 #include <vector>
 
 #include "absl/memory/memory.h"
-#include "rtc_base/checks.h"
 #include "rtc_base/mdns_responder_interface.h"
-#include "rtc_base/message_handler.h"
 #include "rtc_base/network.h"
 #include "rtc_base/socket_address.h"
 #include "rtc_base/string_encode.h"
@@ -31,8 +29,7 @@
 const int kFakeIPv6NetworkPrefixLength = 64;
 
 // Fake network manager that allows us to manually specify the IPs to use.
-class FakeNetworkManager : public NetworkManagerBase,
-                           public MessageHandlerAutoCleanup {
+class FakeNetworkManager : public NetworkManagerBase {
  public:
   FakeNetworkManager() {}
 
@@ -77,28 +74,14 @@
     ++start_count_;
     if (start_count_ == 1) {
       sent_first_update_ = false;
-      rtc::Thread::Current()->Post(RTC_FROM_HERE, this, kUpdateNetworksMessage);
-    } else {
-      if (sent_first_update_) {
-        rtc::Thread::Current()->Post(RTC_FROM_HERE, this,
-                                     kSignalNetworksMessage);
-      }
+      Thread::Current()->PostTask([this] { DoUpdateNetworks(); });
+    } else if (sent_first_update_) {
+      Thread::Current()->PostTask([this] { SignalNetworksChanged(); });
     }
   }
 
   void StopUpdating() override { --start_count_; }
 
-  // MessageHandler interface.
-  void OnMessage(Message* msg) override {
-    if (msg->message_id == kUpdateNetworksMessage) {
-      DoUpdateNetworks();
-    } else if (msg->message_id == kSignalNetworksMessage) {
-      SignalNetworksChanged();
-    } else {
-      RTC_CHECK(false);
-    }
-  }
-
   using NetworkManagerBase::set_default_local_addresses;
   using NetworkManagerBase::set_enumeration_permission;
 
@@ -148,9 +131,6 @@
   int start_count_ = 0;
   bool sent_first_update_ = false;
 
-  static constexpr uint32_t kUpdateNetworksMessage = 1;
-  static constexpr uint32_t kSignalNetworksMessage = 2;
-
   std::unique_ptr<webrtc::MdnsResponderInterface> mdns_responder_;
 };