Use absl::make_unique and absl::WrapUnique directly

Instead of going through our wrappers in ptr_util.h.

This CL was generated by the following script:

  git grep -l ptr_util | xargs perl -pi -e 's,#include "rtc_base/ptr_util.h",#include "absl/memory/memory.h",'
  git grep -l MakeUnique | xargs perl -pi -e 's,\b(rtc::)?MakeUnique\b,absl::make_unique,g'
  git grep -l WrapUnique | xargs perl -pi -e 's,\b(rtc::)?WrapUnique\b,absl::WrapUnique,g'
  git checkout -- rtc_base/ptr_util{.h,_unittest.cc}
  git cl format

Followed by manually adding dependencies on
//third_party/abseil-cpp/absl/memory until `gn check` stopped
complaining.

Bug: webrtc:9473
Change-Id: I89ccd363f070479b8c431eb2c3d404a46eaacc1c
Reviewed-on: https://webrtc-review.googlesource.com/86600
Commit-Queue: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23850}
diff --git a/pc/peerconnection_rtp_unittest.cc b/pc/peerconnection_rtp_unittest.cc
index 2bbf77c..50fe0dc 100644
--- a/pc/peerconnection_rtp_unittest.cc
+++ b/pc/peerconnection_rtp_unittest.cc
@@ -11,6 +11,7 @@
 #include <memory>
 #include <vector>
 
+#include "absl/memory/memory.h"
 #include "api/audio_codecs/builtin_audio_decoder_factory.h"
 #include "api/audio_codecs/builtin_audio_encoder_factory.h"
 #include "api/jsep.h"
@@ -28,7 +29,6 @@
 #include "pc/test/mockpeerconnectionobservers.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/gunit.h"
-#include "rtc_base/ptr_util.h"
 #include "rtc_base/refcountedobject.h"
 #include "rtc_base/scoped_ref_ptr.h"
 #include "rtc_base/thread.h"
@@ -111,11 +111,11 @@
   // adjustment.
   std::unique_ptr<PeerConnectionWrapper> CreatePeerConnectionInternal(
       const RTCConfiguration& config) {
-    auto observer = rtc::MakeUnique<MockPeerConnectionObserver>();
+    auto observer = absl::make_unique<MockPeerConnectionObserver>();
     auto pc = pc_factory_->CreatePeerConnection(config, nullptr, nullptr,
                                                 observer.get());
-    return rtc::MakeUnique<PeerConnectionWrapper>(pc_factory_, pc,
-                                                  std::move(observer));
+    return absl::make_unique<PeerConnectionWrapper>(pc_factory_, pc,
+                                                    std::move(observer));
   }
 };