webrtc: make RTCIceCandidate tcpType optional

for spec compliance the field can/shall be null instead of an empty string
for udp candidates.

BUG=chromium:1125168

Change-Id: I201e6a700ba7c4bcba45f0af6ccf809971d1df0e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2390659Reviewed-by: Harald Alvestrand <hta@chromium.org>
Commit-Queue: Philipp Hancke <philipp.hancke@googlemail.com>
Cr-Commit-Position: refs/heads/master@{#804670}

third_party/blink/renderer/modules/peerconnection/rtc_ice_candidate.cc

@@ -127,7 +127,7 @@ String RTCIceCandidate::type() const {
   return platform_candidate_->Type();
 }
 
-String RTCIceCandidate::tcpType() const {
+base::Optional<String> RTCIceCandidate::tcpType() const {
   return platform_candidate_->TcpType();
 }
 

third_party/blink/renderer/modules/peerconnection/rtc_ice_candidate.h

@@ -65,7 +65,7 @@ class MODULES_EXPORT RTCIceCandidate final : public ScriptWrappable {
   String protocol() const;
   base::Optional<uint16_t> port() const;
   String type() const;
-  String tcpType() const;
+  base::Optional<String> tcpType() const;
   String relatedAddress() const;
   base::Optional<uint16_t> relatedPort() const;
   String usernameFragment() const;

third_party/blink/renderer/platform/peerconnection/rtc_ice_candidate_platform.cc

@@ -76,7 +76,9 @@ void RTCIceCandidatePlatform::PopulateFields(bool use_username_from_candidate) {
     port_ = c.address().port();
   }
   type_ = CandidateTypeToString(c.type());
-  tcp_type_ = String::FromUTF8(c.tcptype().data());
+  if (!c.tcptype().empty()) {
+    tcp_type_ = String::FromUTF8(c.tcptype().data());
+  }
   if (!c.related_address().IsNil()) {
     related_address_ =
         String::FromUTF8(c.related_address().HostAsURIString().data());

third_party/blink/renderer/platform/peerconnection/rtc_ice_candidate_platform.h

@@ -68,7 +68,7 @@ class PLATFORM_EXPORT RTCIceCandidatePlatform final
   const String Protocol() const { return protocol_; }
   const base::Optional<uint16_t>& Port() const { return port_; }
   const String& Type() const { return type_; }
-  const String& TcpType() const { return tcp_type_; }
+  const base::Optional<String>& TcpType() const { return tcp_type_; }
   const String& RelatedAddress() const { return related_address_; }
   const base::Optional<uint16_t>& RelatedPort() const { return related_port_; }
   const String& UsernameFragment() const { return username_fragment_; }
@@ -88,7 +88,7 @@ class PLATFORM_EXPORT RTCIceCandidatePlatform final
   String protocol_;
   base::Optional<uint16_t> port_;
   String type_;
-  String tcp_type_;
+  base::Optional<String> tcp_type_;
   String related_address_;
   base::Optional<uint16_t> related_port_;
   String username_fragment_;

third_party/blink/web_tests/external/wpt/webrtc/RTCIceCandidate-constructor-expected.txt

-This is a testharness.js-based test.
-PASS new RTCIceCandidate()
-PASS new RTCIceCandidate({})
-PASS new RTCIceCandidate({ ... }) with manually filled default values
-PASS new RTCIceCandidate({ sdpMid: null, sdpMLineIndex: null })
-PASS new RTCIceCandidate({ candidate: '' })
-PASS new RTCIceCandidate({ candidate: null })
-PASS new RTCIceCandidate({ ... }) with valid candidate string only
-PASS new RTCIceCandidate({ sdpMid: 'audio' })
-PASS new RTCIceCandidate({ sdpMLineIndex: 0 })
-PASS new RTCIceCandidate({ sdpMid: 'audio', sdpMLineIndex: 0 })
-PASS new RTCIceCandidate({ candidate: '', sdpMid: 'audio' }
-PASS new RTCIceCandidate({ candidate: '', sdpMLineIndex: 0 }
-PASS new RTCIceCandidate({ ... }) with valid candidate string and sdpMid
-PASS new RTCIceCandidate({ ... }) with invalid candidate string and sdpMid
-FAIL new RTCIceCandidate({ ... }) with nondefault values for all fields assert_equals: tcpType expected (object) null but got (string) ""
-PASS new RTCIceCandidate({ ... }) with nondefault values for all fields, tcp candidate
-PASS new RTCIceCandidate({ ... }) with invalid sdpMid
-PASS new RTCIceCandidate({ ... }) with invalid sdpMLineIndex
-Harness: the test ran to completion.
-