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/modules/audio_processing/audio_processing_impl_unittest.cc b/modules/audio_processing/audio_processing_impl_unittest.cc
index 72bd673..292b632 100644
--- a/modules/audio_processing/audio_processing_impl_unittest.cc
+++ b/modules/audio_processing/audio_processing_impl_unittest.cc
@@ -12,7 +12,6 @@
 
 #include <memory>
 
-#include "absl/memory/memory.h"
 #include "api/scoped_refptr.h"
 #include "modules/audio_processing/include/audio_processing.h"
 #include "modules/audio_processing/test/echo_control_mock.h"
@@ -51,12 +50,12 @@
 // to the creation of a new EchoControl object.
 class MockEchoControlFactory : public EchoControlFactory {
  public:
-  MockEchoControlFactory() : next_mock_(absl::make_unique<MockEchoControl>()) {}
+  MockEchoControlFactory() : next_mock_(std::make_unique<MockEchoControl>()) {}
   // Returns a pointer to the next MockEchoControl that this factory creates.
   MockEchoControl* GetNext() const { return next_mock_.get(); }
   std::unique_ptr<EchoControl> Create(int sample_rate_hz) override {
     std::unique_ptr<EchoControl> mock = std::move(next_mock_);
-    next_mock_ = absl::make_unique<MockEchoControl>();
+    next_mock_ = std::make_unique<MockEchoControl>();
     return mock;
   }
 
@@ -215,7 +214,7 @@
      EchoControllerObservesPreAmplifierEchoPathGainChange) {
   // Tests that the echo controller observes an echo path gain change when the
   // pre-amplifier submodule changes the gain.
-  auto echo_control_factory = absl::make_unique<MockEchoControlFactory>();
+  auto echo_control_factory = std::make_unique<MockEchoControlFactory>();
   const auto* echo_control_factory_ptr = echo_control_factory.get();
 
   std::unique_ptr<AudioProcessing> apm(
@@ -258,7 +257,7 @@
      EchoControllerObservesAnalogAgc1EchoPathGainChange) {
   // Tests that the echo controller observes an echo path gain change when the
   // AGC1 analog adaptive submodule changes the analog gain.
-  auto echo_control_factory = absl::make_unique<MockEchoControlFactory>();
+  auto echo_control_factory = std::make_unique<MockEchoControlFactory>();
   const auto* echo_control_factory_ptr = echo_control_factory.get();
 
   std::unique_ptr<AudioProcessing> apm(
@@ -299,7 +298,7 @@
 TEST(AudioProcessingImplTest, EchoControllerObservesPlayoutVolumeChange) {
   // Tests that the echo controller observes an echo path gain change when a
   // playout volume change is reported.
-  auto echo_control_factory = absl::make_unique<MockEchoControlFactory>();
+  auto echo_control_factory = std::make_unique<MockEchoControlFactory>();
   const auto* echo_control_factory_ptr = echo_control_factory.get();
 
   std::unique_ptr<AudioProcessing> apm(