Use std::make_unique instead of absl::make_unique.

WebRTC is now using C++14 so there is no need to use the Abseil version
of std::make_unique.

This CL has been created with the following steps:

git grep -l absl::make_unique | sort | uniq > /tmp/make_unique.txt
git grep -l absl::WrapUnique | sort | uniq > /tmp/wrap_unique.txt
git grep -l "#include <memory>" | sort | uniq > /tmp/memory.txt

diff --new-line-format="" --unchanged-line-format="" \
  /tmp/make_unique.txt /tmp/wrap_unique.txt | sort | \
  uniq > /tmp/only_make_unique.txt
diff --new-line-format="" --unchanged-line-format="" \
  /tmp/only_make_unique.txt /tmp/memory.txt | \
  xargs grep -l "absl/memory" > /tmp/add-memory.txt

git grep -l "\babsl::make_unique\b" | \
  xargs sed -i "s/\babsl::make_unique\b/std::make_unique/g"

git checkout PRESUBMIT.py abseil-in-webrtc.md

cat /tmp/add-memory.txt | \
  xargs sed -i \
  's/#include "absl\/memory\/memory.h"/#include <memory>/g'
git cl format
# Manual fix order of the new inserted #include <memory>

cat /tmp/only_make_unique | xargs grep -l "#include <memory>" | \
  xargs sed -i '/#include "absl\/memory\/memory.h"/d'

git ls-files | grep BUILD.gn | \
  xargs sed -i '/\/\/third_party\/abseil-cpp\/absl\/memory/d'

python tools_webrtc/gn_check_autofix.py \
  -m tryserver.webrtc -b linux_rel

# Repead the gn_check_autofix step for other platforms

git ls-files | grep BUILD.gn | \
  xargs sed -i 's/absl\/memory:memory/absl\/memory/g'
git cl format

Bug: webrtc:10945
Change-Id: I3fe28ea80f4dd3ba3cf28effd151d5e1f19aff89
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/153221
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Alessio Bazzica <alessiob@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29209}
diff --git a/test/test_main_lib.cc b/test/test_main_lib.cc
index c9b45c6..bb41e65 100644
--- a/test/test_main_lib.cc
+++ b/test/test_main_lib.cc
@@ -11,11 +11,11 @@
 #include "test/test_main_lib.h"
 
 #include <fstream>
+#include <memory>
 #include <string>
 
 #include "absl/flags/flag.h"
 #include "absl/flags/parse.h"
-#include "absl/memory/memory.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/event_tracer.h"
 #include "rtc_base/logging.h"
@@ -138,7 +138,7 @@
     webrtc::metrics::Enable();
 
 #if defined(WEBRTC_WIN)
-    winsock_init_ = absl::make_unique<rtc::WinsockInitializer>();
+    winsock_init_ = std::make_unique<rtc::WinsockInitializer>();
 #endif
 
     // Initialize SSL which are used by several tests.
@@ -214,7 +214,7 @@
 }  // namespace
 
 std::unique_ptr<TestMain> TestMain::Create() {
-  return absl::make_unique<TestMainImpl>();
+  return std::make_unique<TestMainImpl>();
 }
 
 }  // namespace webrtc