Add steps logging into PC test framework

For now there are a lot of logging from signaing phase and from WebRTC
internal components during the call. So this CL will add log entries
about starting or ending important phase of the test to easier determine
when what happend.

Bug: webrtc:10138
Change-Id: I4bf30d687be6ba830daff4c1d6f2e72afd5eb43d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/149064
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28891}
diff --git a/test/pc/e2e/peer_connection_quality_test.cc b/test/pc/e2e/peer_connection_quality_test.cc
index 4d7afb6..e90b170 100644
--- a/test/pc/e2e/peer_connection_quality_test.cc
+++ b/test/pc/e2e/peer_connection_quality_test.cc
@@ -330,6 +330,8 @@
                                       return kAliveMessageLogInterval;
                                     });
 
+  RTC_LOG(INFO) << "Configuration is done. Now Alice is calling to Bob...";
+
   // Setup call.
   signaling_thread->Invoke<void>(
       RTC_FROM_HERE,
@@ -366,6 +368,8 @@
     done.Wait(run_params.run_duration.ms());
   }
 
+  RTC_LOG(INFO) << "Test is done, initiating disconnect sequence.";
+
   task_queue_->SendTask([this]() {
     RTC_DCHECK_RUN_ON(task_queue_.get());
     stats_polling_task_.Stop();
@@ -390,6 +394,7 @@
       rtc::Bind(&PeerConnectionE2EQualityTest::TearDownCallOnSignalingThread,
                 this));
   Timestamp end_time = Now();
+  RTC_LOG(INFO) << "All peers are disconnected.";
   {
     rtc::CritScope crit(&lock_);
     real_test_duration_ = end_time - start_time_;
@@ -856,6 +861,7 @@
   // This means that ICE and DTLS are connected.
   ASSERT_TRUE_WAIT(bob_->IsIceConnected(), kDefaultTimeoutMs);
   ASSERT_TRUE_WAIT(alice_->IsIceConnected(), kDefaultTimeoutMs);
+  RTC_LOG(INFO) << "Call is started (all peers are connected).";
 }
 
 void PeerConnectionE2EQualityTest::ExchangeOfferAnswer(