compare Optional<unsigned> only to unsigned integers

more standard optional<T> inlines compares instead of converting second argument to T.
that leads to warnings about comparing unsigned to signed integers.

Bug: webrtc:9078
Change-Id: I43cc729d3b85d789b0c394064dc7e11dc27a37aa
Reviewed-on: https://webrtc-review.googlesource.com/66782
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22779}
diff --git a/logging/rtc_event_log/encoder/rtc_event_log_encoder_unittest.cc b/logging/rtc_event_log/encoder/rtc_event_log_encoder_unittest.cc
index a8e6e8d..6d88298 100644
--- a/logging/rtc_event_log/encoder/rtc_event_log_encoder_unittest.cc
+++ b/logging/rtc_event_log/encoder/rtc_event_log_encoder_unittest.cc
@@ -417,7 +417,7 @@
 
 TEST_P(RtcEventLogEncoderTest, RtcEventProbeResultSuccess) {
   const int id = RandomPositiveInt();
-  const int bitrate_bps = RandomBitrate();
+  const uint64_t bitrate_bps = rtc::checked_cast<uint64_t>(RandomBitrate());
 
   auto event = rtc::MakeUnique<RtcEventProbeResultSuccess>(id, bitrate_bps);
   const int64_t timestamp_us = event->timestamp_us_;
@@ -433,7 +433,6 @@
 
   EXPECT_EQ(parsed_log_.GetTimestamp(0), timestamp_us);
   EXPECT_EQ(rtc::dchecked_cast<int>(parsed_event.id), id);
-  ASSERT_TRUE(parsed_event.bitrate_bps);
   EXPECT_EQ(parsed_event.bitrate_bps, bitrate_bps);
   ASSERT_FALSE(parsed_event.failure_reason);
 }
diff --git a/modules/audio_coding/audio_network_adaptor/audio_network_adaptor_impl_unittest.cc b/modules/audio_coding/audio_network_adaptor/audio_network_adaptor_impl_unittest.cc
index c437918..574b699 100644
--- a/modules/audio_coding/audio_network_adaptor/audio_network_adaptor_impl_unittest.cc
+++ b/modules/audio_coding/audio_network_adaptor/audio_network_adaptor_impl_unittest.cc
@@ -314,12 +314,12 @@
 
   auto ana_stats = states.audio_network_adaptor->GetStats();
 
-  EXPECT_EQ(ana_stats.bitrate_action_counter, 2);
-  EXPECT_EQ(ana_stats.channel_action_counter, 2);
-  EXPECT_EQ(ana_stats.dtx_action_counter, 2);
-  EXPECT_EQ(ana_stats.fec_action_counter, 2);
-  EXPECT_EQ(ana_stats.frame_length_increase_counter, 1);
-  EXPECT_EQ(ana_stats.frame_length_decrease_counter, 1);
+  EXPECT_EQ(ana_stats.bitrate_action_counter, 2u);
+  EXPECT_EQ(ana_stats.channel_action_counter, 2u);
+  EXPECT_EQ(ana_stats.dtx_action_counter, 2u);
+  EXPECT_EQ(ana_stats.fec_action_counter, 2u);
+  EXPECT_EQ(ana_stats.frame_length_increase_counter, 1u);
+  EXPECT_EQ(ana_stats.frame_length_decrease_counter, 1u);
   EXPECT_EQ(ana_stats.uplink_packet_loss_fraction, 0.1f);
 }
 
diff --git a/modules/video_coding/video_codec_initializer.cc b/modules/video_coding/video_codec_initializer.cc
index 5ba659d..e340b46 100644
--- a/modules/video_coding/video_codec_initializer.cc
+++ b/modules/video_coding/video_codec_initializer.cc
@@ -89,7 +89,7 @@
       break;
     case VideoEncoderConfig::ContentType::kScreen:
       video_codec.mode = kScreensharing;
-      if (!streams.empty() && streams[0].num_temporal_layers == 2) {
+      if (!streams.empty() && streams[0].num_temporal_layers == 2u) {
         video_codec.targetBitrate = streams[0].target_bitrate_bps / 1000;
       }
       break;
diff --git a/rtc_base/string_to_number_unittest.cc b/rtc_base/string_to_number_unittest.cc
index f5e5b573..538ee10 100644
--- a/rtc_base/string_to_number_unittest.cc
+++ b/rtc_base/string_to_number_unittest.cc
@@ -42,15 +42,16 @@
   using T = TypeParam;
   constexpr T min_value = std::numeric_limits<T>::lowest();
   constexpr T max_value = std::numeric_limits<T>::max();
+  constexpr T zero_value = 0;
   const std::string min_string = std::to_string(min_value);
   const std::string max_string = std::to_string(max_value);
   EXPECT_EQ(min_value, StringToNumber<T>(min_string));
   EXPECT_EQ(min_value, StringToNumber<T>(min_string.c_str()));
   EXPECT_EQ(max_value, StringToNumber<T>(max_string));
   EXPECT_EQ(max_value, StringToNumber<T>(max_string.c_str()));
-  EXPECT_EQ(0, StringToNumber<T>("0"));
-  EXPECT_EQ(0, StringToNumber<T>("-0"));
-  EXPECT_EQ(0, StringToNumber<T>(std::string("-0000000000000")));
+  EXPECT_EQ(zero_value, StringToNumber<T>("0"));
+  EXPECT_EQ(zero_value, StringToNumber<T>("-0"));
+  EXPECT_EQ(zero_value, StringToNumber<T>(std::string("-0000000000000")));
 }
 
 TYPED_TEST_P(BasicNumberTest, TestInvalidNumbers) {