Enable DTLS 1.3 by default  in Chromium

Bug: webrtc:383141571
Change-Id: If0b4f5b9866f39629609291723565f4183db7472
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/409562
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Auto-Submit: Guido Urdaneta <guidou@webrtc.org>
Reviewed-by: Jonas Oreland <jonaso@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#45662}

rtc_base/openssl_stream_adapter.cc

diff --git a/rtc_base/openssl_stream_adapter.cc b/rtc_base/openssl_stream_adapter.cc
index 2b45d37..942cb02 100644
--- a/rtc_base/openssl_stream_adapter.cc
+++ b/rtc_base/openssl_stream_adapter.cc
@@ -140,21 +140,36 @@
 #endif
 
 int GetForceDtls13(const FieldTrialsView* field_trials) {
-  if (field_trials == nullptr) {
-    return kForceDtls13Off;
-  }
 #ifdef DTLS1_3_VERSION
-  if (field_trials->IsEnabled("WebRTC-ForceDtls13")) {
-    RTC_LOG(LS_WARNING) << "WebRTC-ForceDtls13 Enabled";
-    return kForceDtls13Enabled;
+  if (field_trials) {
+#if defined(WEBRTC_CHROMIUM_BUILD)
+    if (field_trials->IsDisabled("WebRTC-ForceDtls13")) {
+      RTC_LOG(LS_WARNING) << "WebRTC-ForceDtls13 Disabled";
+      return kForceDtls13Off;
+    }
+#else
+    if (field_trials->IsEnabled("WebRTC-ForceDtls13")) {
+      RTC_LOG(LS_WARNING) << "WebRTC-ForceDtls13 Enabled";
+      return kForceDtls13Enabled;
+    }
+#endif  // defined(WEBRTC_CHROMIUM_BUILD)
+    if (field_trials->Lookup("WebRTC-ForceDtls13") == "Only") {
+      RTC_LOG(LS_WARNING) << "WebRTC-ForceDtls13 Only";
+      return kForceDtls13Only;
+    }
   }
-  if (field_trials->Lookup("WebRTC-ForceDtls13") == "Only") {
-    RTC_LOG(LS_WARNING) << "WebRTC-ForceDtls13 Only";
-    return kForceDtls13Only;
-  }
+  // Default behavior:
+#if defined(WEBRTC_CHROMIUM_BUILD)
+  RTC_LOG(LS_WARNING) << "WebRTC-ForceDtls13 Enabled";
+  return kForceDtls13Enabled;
+#else
   RTC_LOG(LS_WARNING) << "WebRTC-ForceDtls13 Disabled";
-#endif
   return kForceDtls13Off;
+#endif  // defined(WEBRTC_CHROMIUM_BUILD)
+
+#else
+  return kForceDtls13Off;
+#endif  // DTLS1_3_VERSION
 }
 
 }  // namespace