Remove default field trials and task queue factory in CreatePeerConnectionFactory function

When they are unset, internally same defaults will be created by Environment, i.e., creating them in CreatePeerConnectionFactory is redundant
(https://webrtc.googlesource.com/src/+/refs/heads/main/api/environment/environment_factory.cc#96)

This would simplify changing the default in the future, and demonstrates that by default it is better to leave these dependencies unset.

Bug: webrtc:42226001
Change-Id: I8bf8614b9e8ca4062939e71d45e67cf2da1558c6
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/350742
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#42322}
diff --git a/api/BUILD.gn b/api/BUILD.gn
index b714309..464e1be 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -89,8 +89,6 @@
       "audio:audio_mixer_api",
       "audio:audio_processing",
       "audio_codecs:audio_codecs_api",
-      "task_queue:default_task_queue_factory",
-      "transport:field_trial_based_config",
       "video_codecs:video_codecs_api",
     ]
   }
diff --git a/api/create_peerconnection_factory.cc b/api/create_peerconnection_factory.cc
index 46105a2..e5ba20f 100644
--- a/api/create_peerconnection_factory.cc
+++ b/api/create_peerconnection_factory.cc
@@ -19,8 +19,6 @@
 #include "api/peer_connection_interface.h"
 #include "api/rtc_event_log/rtc_event_log_factory.h"
 #include "api/scoped_refptr.h"
-#include "api/task_queue/default_task_queue_factory.h"
-#include "api/transport/field_trial_based_config.h"
 #include "rtc_base/thread.h"
 
 namespace webrtc {
@@ -38,16 +36,10 @@
     rtc::scoped_refptr<AudioProcessing> audio_processing,
     std::unique_ptr<AudioFrameProcessor> audio_frame_processor,
     std::unique_ptr<FieldTrialsView> field_trials) {
-  if (!field_trials) {
-    field_trials = std::make_unique<webrtc::FieldTrialBasedConfig>();
-  }
-
   PeerConnectionFactoryDependencies dependencies;
   dependencies.network_thread = network_thread;
   dependencies.worker_thread = worker_thread;
   dependencies.signaling_thread = signaling_thread;
-  dependencies.task_queue_factory =
-      CreateDefaultTaskQueueFactory(field_trials.get());
   dependencies.event_log_factory = std::make_unique<RtcEventLogFactory>();
   dependencies.trials = std::move(field_trials);