Reland of: Adding error output param to SetConfiguration, using new RTCError type.

Most notably, will return "INVALID_MODIFICATION" if a field in the
configuration was modified and modification of that field isn't supported.

Also changing RTCError to a class that wraps an enum type, because it will
eventually need to hold other information (like SDP line number), to match
the RTCError that was recently added to the spec:
https://github.com/w3c/webrtc-pc/pull/850

BUG=webrtc:6916

Review-Url: https://codereview.webrtc.org/2587133004
Cr-Original-Commit-Position: refs/heads/master@{#15777}
Committed: https://chromium.googlesource.com/external/webrtc/+/7a5fa6cd6173adbe32aedc1aedc872478121f5ed
Review-Url: https://codereview.webrtc.org/2587133004
Cr-Commit-Position: refs/heads/master@{#16016}
diff --git a/webrtc/api/peerconnection.cc b/webrtc/api/peerconnection.cc
index 1d85e73..2f21e0c 100644
--- a/webrtc/api/peerconnection.cc
+++ b/webrtc/api/peerconnection.cc
@@ -49,6 +49,8 @@
 using webrtc::MediaConstraintsInterface;
 using webrtc::MediaStreamInterface;
 using webrtc::PeerConnectionInterface;
+using webrtc::RTCError;
+using webrtc::RTCErrorType;
 using webrtc::RtpSenderInternal;
 using webrtc::RtpSenderInterface;
 using webrtc::RtpSenderProxy;
@@ -208,10 +210,11 @@
 
 // Adds a STUN or TURN server to the appropriate list,
 // by parsing |url| and using the username/password in |server|.
-bool ParseIceServerUrl(const PeerConnectionInterface::IceServer& server,
-                       const std::string& url,
-                       cricket::ServerAddresses* stun_servers,
-                       std::vector<cricket::RelayServerConfig>* turn_servers) {
+RTCErrorType ParseIceServerUrl(
+    const PeerConnectionInterface::IceServer& server,
+    const std::string& url,
+    cricket::ServerAddresses* stun_servers,
+    std::vector<cricket::RelayServerConfig>* turn_servers) {
   // draft-nandakumar-rtcweb-stun-uri-01
   // stunURI       = scheme ":" stun-host [ ":" stun-port ]
   // scheme        = "stun" / "stuns"
@@ -239,14 +242,14 @@
     rtc::tokenize_with_empty_tokens(uri_transport_param, '=', &tokens);
     if (tokens[0] != kTransport) {
       LOG(LS_WARNING) << "Invalid transport parameter key.";
-      return false;
+      return RTCErrorType::SYNTAX_ERROR;
     }
     if (tokens.size() < 2 ||
         !cricket::StringToProto(tokens[1].c_str(), &turn_transport_type) ||
         (turn_transport_type != cricket::PROTO_UDP &&
          turn_transport_type != cricket::PROTO_TCP)) {
       LOG(LS_WARNING) << "Transport param should always be udp or tcp.";
-      return false;
+      return RTCErrorType::SYNTAX_ERROR;
     }
   }
 
@@ -256,7 +259,7 @@
                                        &service_type,
                                        &hoststring)) {
     LOG(LS_WARNING) << "Invalid transport parameter in ICE URI: " << url;
-    return false;
+    return RTCErrorType::SYNTAX_ERROR;
   }
 
   // GetServiceTypeAndHostnameFromUri should never give an empty hoststring
@@ -269,12 +272,12 @@
   std::string username(server.username);
   if (tokens.size() > kTurnHostTokensNum) {
     LOG(LS_WARNING) << "Invalid user@hostname format: " << hoststring;
-    return false;
+    return RTCErrorType::SYNTAX_ERROR;
   }
   if (tokens.size() == kTurnHostTokensNum) {
     if (tokens[0].empty() || tokens[1].empty()) {
       LOG(LS_WARNING) << "Invalid user@hostname format: " << hoststring;
-      return false;
+      return RTCErrorType::SYNTAX_ERROR;
     }
     username.assign(rtc::s_url_decode(tokens[0]));
     hoststring = tokens[1];
@@ -291,12 +294,12 @@
   std::string address;
   if (!ParseHostnameAndPortFromString(hoststring, &address, &port)) {
     LOG(WARNING) << "Invalid hostname format: " << uri_without_transport;
-    return false;
+    return RTCErrorType::SYNTAX_ERROR;
   }
 
   if (port <= 0 || port > 0xffff) {
     LOG(WARNING) << "Invalid port: " << port;
-    return false;
+    return RTCErrorType::SYNTAX_ERROR;
   }
 
   switch (service_type) {
@@ -306,6 +309,11 @@
       break;
     case TURN:
     case TURNS: {
+      if (username.empty() || server.password.empty()) {
+        // The WebRTC spec requires throwing an InvalidAccessError when username
+        // or credential are ommitted; this is the native equivalent.
+        return RTCErrorType::INVALID_PARAMETER;
+      }
       cricket::RelayServerConfig config = cricket::RelayServerConfig(
           address, port, username, server.password, turn_transport_type);
       if (server.tls_cert_policy ==
@@ -316,12 +324,13 @@
       turn_servers->push_back(config);
       break;
     }
-    case INVALID:
     default:
-      LOG(WARNING) << "Configuration not supported: " << url;
-      return false;
+      // We shouldn't get to this point with an invalid service_type, we should
+      // have returned an error already.
+      RTC_DCHECK(false) << "Unexpected service type";
+      return RTCErrorType::INTERNAL_ERROR;
   }
-  return true;
+  return RTCErrorType::NONE;
 }
 
 // Check if we can send |new_stream| on a PeerConnection.
@@ -433,11 +442,19 @@
   }
 }
 
+// Helper to set an error and return from a method.
+bool SafeSetError(webrtc::RTCErrorType type, webrtc::RTCError* error) {
+  if (error) {
+    error->set_type(type);
+  }
+  return type == webrtc::RTCErrorType::NONE;
+}
+
 }  // namespace
 
 namespace webrtc {
 
-static const char* const kRtcErrorNames[] = {
+static const char* const kRTCErrorTypeNames[] = {
     "NONE",
     "UNSUPPORTED_PARAMETER",
     "INVALID_PARAMETER",
@@ -448,12 +465,82 @@
     "NETWORK_ERROR",
     "INTERNAL_ERROR",
 };
+static_assert(static_cast<int>(RTCErrorType::INTERNAL_ERROR) ==
+                  (arraysize(kRTCErrorTypeNames) - 1),
+              "kRTCErrorTypeNames must have as many strings as RTCErrorType "
+              "has values.");
 
-std::ostream& operator<<(std::ostream& stream, RtcError error) {
+std::ostream& operator<<(std::ostream& stream, RTCErrorType error) {
   int index = static_cast<int>(error);
-  RTC_CHECK(index < static_cast<int>(sizeof(kRtcErrorNames) /
-                                     sizeof(kRtcErrorNames[0])));
-  return stream << kRtcErrorNames[index];
+  return stream << kRTCErrorTypeNames[index];
+}
+
+bool PeerConnectionInterface::RTCConfiguration::operator==(
+    const PeerConnectionInterface::RTCConfiguration& o) const {
+  // This static_assert prevents us from accidentally breaking operator==.
+  struct stuff_being_tested_for_equality {
+    IceTransportsType type;
+    IceServers servers;
+    BundlePolicy bundle_policy;
+    RtcpMuxPolicy rtcp_mux_policy;
+    TcpCandidatePolicy tcp_candidate_policy;
+    CandidateNetworkPolicy candidate_network_policy;
+    int audio_jitter_buffer_max_packets;
+    bool audio_jitter_buffer_fast_accelerate;
+    int ice_connection_receiving_timeout;
+    int ice_backup_candidate_pair_ping_interval;
+    ContinualGatheringPolicy continual_gathering_policy;
+    std::vector<rtc::scoped_refptr<rtc::RTCCertificate>> certificates;
+    bool prioritize_most_likely_ice_candidate_pairs;
+    struct cricket::MediaConfig media_config;
+    bool disable_ipv6;
+    bool enable_rtp_data_channel;
+    bool enable_quic;
+    rtc::Optional<int> screencast_min_bitrate;
+    rtc::Optional<bool> combined_audio_video_bwe;
+    rtc::Optional<bool> enable_dtls_srtp;
+    int ice_candidate_pool_size;
+    bool prune_turn_ports;
+    bool presume_writable_when_fully_relayed;
+    bool enable_ice_renomination;
+    bool redetermine_role_on_ice_restart;
+  };
+  static_assert(sizeof(stuff_being_tested_for_equality) == sizeof(*this),
+                "Did you add something to RTCConfiguration and forget to "
+                "update operator==?");
+  return type == o.type && servers == o.servers &&
+         bundle_policy == o.bundle_policy &&
+         rtcp_mux_policy == o.rtcp_mux_policy &&
+         tcp_candidate_policy == o.tcp_candidate_policy &&
+         candidate_network_policy == o.candidate_network_policy &&
+         audio_jitter_buffer_max_packets == o.audio_jitter_buffer_max_packets &&
+         audio_jitter_buffer_fast_accelerate ==
+             o.audio_jitter_buffer_fast_accelerate &&
+         ice_connection_receiving_timeout ==
+             o.ice_connection_receiving_timeout &&
+         ice_backup_candidate_pair_ping_interval ==
+             o.ice_backup_candidate_pair_ping_interval &&
+         continual_gathering_policy == o.continual_gathering_policy &&
+         certificates == o.certificates &&
+         prioritize_most_likely_ice_candidate_pairs ==
+             o.prioritize_most_likely_ice_candidate_pairs &&
+         media_config == o.media_config && disable_ipv6 == o.disable_ipv6 &&
+         enable_rtp_data_channel == o.enable_rtp_data_channel &&
+         enable_quic == o.enable_quic &&
+         screencast_min_bitrate == o.screencast_min_bitrate &&
+         combined_audio_video_bwe == o.combined_audio_video_bwe &&
+         enable_dtls_srtp == o.enable_dtls_srtp &&
+         ice_candidate_pool_size == o.ice_candidate_pool_size &&
+         prune_turn_ports == o.prune_turn_ports &&
+         presume_writable_when_fully_relayed ==
+             o.presume_writable_when_fully_relayed &&
+         enable_ice_renomination == o.enable_ice_renomination &&
+         redetermine_role_on_ice_restart == o.redetermine_role_on_ice_restart;
+}
+
+bool PeerConnectionInterface::RTCConfiguration::operator!=(
+    const PeerConnectionInterface::RTCConfiguration& o) const {
+  return !(*this == o);
 }
 
 // Generate a RTCP CNAME when a PeerConnection is created.
@@ -555,28 +642,33 @@
   return mandatory_constraints_satisfied == constraints->GetMandatory().size();
 }
 
-bool ParseIceServers(const PeerConnectionInterface::IceServers& servers,
-                     cricket::ServerAddresses* stun_servers,
-                     std::vector<cricket::RelayServerConfig>* turn_servers) {
+RTCErrorType ParseIceServers(
+    const PeerConnectionInterface::IceServers& servers,
+    cricket::ServerAddresses* stun_servers,
+    std::vector<cricket::RelayServerConfig>* turn_servers) {
   for (const webrtc::PeerConnectionInterface::IceServer& server : servers) {
     if (!server.urls.empty()) {
       for (const std::string& url : server.urls) {
         if (url.empty()) {
           LOG(LS_ERROR) << "Empty uri.";
-          return false;
+          return RTCErrorType::SYNTAX_ERROR;
         }
-        if (!ParseIceServerUrl(server, url, stun_servers, turn_servers)) {
-          return false;
+        RTCErrorType err =
+            ParseIceServerUrl(server, url, stun_servers, turn_servers);
+        if (err != RTCErrorType::NONE) {
+          return err;
         }
       }
     } else if (!server.uri.empty()) {
       // Fallback to old .uri if new .urls isn't present.
-      if (!ParseIceServerUrl(server, server.uri, stun_servers, turn_servers)) {
-        return false;
+      RTCErrorType err =
+          ParseIceServerUrl(server, server.uri, stun_servers, turn_servers);
+      if (err != RTCErrorType::NONE) {
+        return err;
       }
     } else {
       LOG(LS_ERROR) << "Empty uri.";
-      return false;
+      return RTCErrorType::SYNTAX_ERROR;
     }
   }
   // Candidates must have unique priorities, so that connectivity checks
@@ -586,7 +678,7 @@
     // First in the list gets highest priority.
     turn_server.priority = priority--;
   }
-  return true;
+  return RTCErrorType::NONE;
 }
 
 PeerConnection::PeerConnection(PeerConnectionFactory* factory)
@@ -633,12 +725,18 @@
     std::unique_ptr<rtc::RTCCertificateGeneratorInterface> cert_generator,
     PeerConnectionObserver* observer) {
   TRACE_EVENT0("webrtc", "PeerConnection::Initialize");
-  RTC_DCHECK(observer != nullptr);
+  if (!allocator) {
+    LOG(LS_ERROR) << "PeerConnection initialized without a PortAllocator? "
+                  << "This shouldn't happen if using PeerConnectionFactory.";
+    return false;
+  }
   if (!observer) {
+    // TODO(deadbeef): Why do we do this?
+    LOG(LS_ERROR) << "PeerConnection initialized without a "
+                  << "PeerConnectionObserver";
     return false;
   }
   observer_ = observer;
-
   port_allocator_ = std::move(allocator);
 
   // The port allocator lives on the network thread and should be initialized
@@ -1301,7 +1399,8 @@
   return configuration_;
 }
 
-bool PeerConnection::SetConfiguration(const RTCConfiguration& configuration) {
+bool PeerConnection::SetConfiguration(const RTCConfiguration& configuration,
+                                      RTCError* error) {
   TRACE_EVENT0("webrtc", "PeerConnection::SetConfiguration");
 
   if (session_->local_description() &&
@@ -1309,32 +1408,61 @@
           configuration_.ice_candidate_pool_size) {
     LOG(LS_ERROR) << "Can't change candidate pool size after calling "
                      "SetLocalDescription.";
-    return false;
-  }
-  // TODO(deadbeef): Return false and log an error if there are any unsupported
-  // modifications.
-  if (port_allocator_) {
-    if (!network_thread()->Invoke<bool>(
-            RTC_FROM_HERE,
-            rtc::Bind(&PeerConnection::ReconfigurePortAllocator_n, this,
-                      configuration))) {
-      LOG(LS_ERROR) << "Failed to apply configuration to PortAllocator.";
-      return false;
-    }
+    return SafeSetError(RTCErrorType::INVALID_MODIFICATION, error);
   }
 
-  // TODO(deadbeef): Shouldn't have to hop to the network thread twice...
-  session_->SetIceConfig(session_->ParseIceConfig(configuration));
+  // The simplest (and most future-compatible) way to tell if the config was
+  // modified in an invalid way is to copy each property we do support
+  // modifying, then use operator==. There are far more properties we don't
+  // support modifying than those we do, and more could be added.
+  RTCConfiguration modified_config = configuration_;
+  modified_config.servers = configuration.servers;
+  modified_config.type = configuration.type;
+  modified_config.ice_candidate_pool_size =
+      configuration.ice_candidate_pool_size;
+  modified_config.prune_turn_ports = configuration.prune_turn_ports;
+  if (configuration != modified_config) {
+    LOG(LS_ERROR) << "Modifying the configuration in an unsupported way.";
+    return SafeSetError(RTCErrorType::INVALID_MODIFICATION, error);
+  }
+
+  // Note that this isn't possible through chromium, since it's an unsigned
+  // short in WebIDL.
+  if (configuration.ice_candidate_pool_size < 0 ||
+      configuration.ice_candidate_pool_size > UINT16_MAX) {
+    return SafeSetError(RTCErrorType::INVALID_RANGE, error);
+  }
+
+  // Parse ICE servers before hopping to network thread.
+  cricket::ServerAddresses stun_servers;
+  std::vector<cricket::RelayServerConfig> turn_servers;
+  RTCErrorType parse_error =
+      ParseIceServers(configuration.servers, &stun_servers, &turn_servers);
+  if (parse_error != RTCErrorType::NONE) {
+    return SafeSetError(parse_error, error);
+  }
+
+  // In theory this shouldn't fail.
+  if (!network_thread()->Invoke<bool>(
+          RTC_FROM_HERE,
+          rtc::Bind(&PeerConnection::ReconfigurePortAllocator_n, this,
+                    stun_servers, turn_servers, modified_config.type,
+                    modified_config.ice_candidate_pool_size,
+                    modified_config.prune_turn_ports))) {
+    LOG(LS_ERROR) << "Failed to apply configuration to PortAllocator.";
+    return SafeSetError(RTCErrorType::INTERNAL_ERROR, error);
+  }
 
   // As described in JSEP, calling setConfiguration with new ICE servers or
   // candidate policy must set a "needs-ice-restart" bit so that the next offer
   // triggers an ICE restart which will pick up the changes.
-  if (configuration.servers != configuration_.servers ||
-      configuration.type != configuration_.type) {
+  if (modified_config.servers != configuration_.servers ||
+      modified_config.type != configuration_.type ||
+      modified_config.prune_turn_ports != configuration_.prune_turn_ports) {
     session_->SetNeedsIceRestartFlag();
   }
-  configuration_ = configuration;
-  return true;
+  configuration_ = modified_config;
+  return SafeSetError(RTCErrorType::NONE, error);
 }
 
 bool PeerConnection::AddIceCandidate(
@@ -1361,7 +1489,7 @@
   }
 
   // Send information about IPv4/IPv6 status.
-  if (uma_observer_ && port_allocator_) {
+  if (uma_observer_) {
     port_allocator_->SetMetricsObserver(uma_observer_);
     if (port_allocator_->flags() & cricket::PORTALLOCATOR_ENABLE_IPV6) {
       uma_observer_->IncrementEnumCounter(
@@ -2374,7 +2502,8 @@
     const RTCConfiguration& configuration) {
   cricket::ServerAddresses stun_servers;
   std::vector<cricket::RelayServerConfig> turn_servers;
-  if (!ParseIceServers(configuration.servers, &stun_servers, &turn_servers)) {
+  if (ParseIceServers(configuration.servers, &stun_servers, &turn_servers) !=
+      RTCErrorType::NONE) {
     return false;
   }
 
@@ -2420,19 +2549,17 @@
 }
 
 bool PeerConnection::ReconfigurePortAllocator_n(
-    const RTCConfiguration& configuration) {
-  cricket::ServerAddresses stun_servers;
-  std::vector<cricket::RelayServerConfig> turn_servers;
-  if (!ParseIceServers(configuration.servers, &stun_servers, &turn_servers)) {
-    return false;
-  }
+    const cricket::ServerAddresses& stun_servers,
+    const std::vector<cricket::RelayServerConfig>& turn_servers,
+    IceTransportsType type,
+    int candidate_pool_size,
+    bool prune_turn_ports) {
   port_allocator_->set_candidate_filter(
-      ConvertIceTransportTypeToCandidateFilter(configuration.type));
+      ConvertIceTransportTypeToCandidateFilter(type));
   // Call this last since it may create pooled allocator sessions using the
   // candidate filter set above.
   return port_allocator_->SetConfiguration(
-      stun_servers, turn_servers, configuration.ice_candidate_pool_size,
-      configuration.prune_turn_ports);
+      stun_servers, turn_servers, candidate_pool_size, prune_turn_ports);
 }
 
 bool PeerConnection::StartRtcEventLog_w(rtc::PlatformFile file,
diff --git a/webrtc/api/peerconnection.h b/webrtc/api/peerconnection.h
index 5269e3a..82dc8ed 100644
--- a/webrtc/api/peerconnection.h
+++ b/webrtc/api/peerconnection.h
@@ -54,10 +54,12 @@
                                cricket::MediaSessionOptions* session_options);
 
 // Parses the URLs for each server in |servers| to build |stun_servers| and
-// |turn_servers|.
-bool ParseIceServers(const PeerConnectionInterface::IceServers& servers,
-                     cricket::ServerAddresses* stun_servers,
-                     std::vector<cricket::RelayServerConfig>* turn_servers);
+// |turn_servers|. Can return SYNTAX_ERROR if the URL is malformed, or
+// INVALID_PARAMETER if a TURN server is missing |username| or |password|.
+RTCErrorType ParseIceServers(
+    const PeerConnectionInterface::IceServers& servers,
+    cricket::ServerAddresses* stun_servers,
+    std::vector<cricket::RelayServerConfig>* turn_servers);
 
 // PeerConnection implements the PeerConnectionInterface interface.
 // It uses WebRtcSession to implement the PeerConnection functionality.
@@ -137,7 +139,12 @@
                             SessionDescriptionInterface* desc) override;
   PeerConnectionInterface::RTCConfiguration GetConfiguration() override;
   bool SetConfiguration(
-      const PeerConnectionInterface::RTCConfiguration& configuration) override;
+      const PeerConnectionInterface::RTCConfiguration& configuration,
+      RTCError* error) override;
+  bool SetConfiguration(
+      const PeerConnectionInterface::RTCConfiguration& configuration) override {
+    return SetConfiguration(configuration, nullptr);
+  }
   bool AddIceCandidate(const IceCandidateInterface* candidate) override;
   bool RemoveIceCandidates(
       const std::vector<cricket::Candidate>& candidates) override;
@@ -373,9 +380,14 @@
 
   // Called when first configuring the port allocator.
   bool InitializePortAllocator_n(const RTCConfiguration& configuration);
-  // Called when SetConfiguration is called. Only a subset of the configuration
-  // is applied.
-  bool ReconfigurePortAllocator_n(const RTCConfiguration& configuration);
+  // Called when SetConfiguration is called to apply the supported subset
+  // of the configuration on the network thread.
+  bool ReconfigurePortAllocator_n(
+      const cricket::ServerAddresses& stun_servers,
+      const std::vector<cricket::RelayServerConfig>& turn_servers,
+      IceTransportsType type,
+      int candidate_pool_size,
+      bool prune_turn_ports);
 
   // Starts recording an Rtc EventLog using the supplied platform file.
   // This function should only be called from the worker thread.
diff --git a/webrtc/api/peerconnection_unittest.cc b/webrtc/api/peerconnection_unittest.cc
index 4fe29f2..c27e53f 100644
--- a/webrtc/api/peerconnection_unittest.cc
+++ b/webrtc/api/peerconnection_unittest.cc
@@ -2621,6 +2621,10 @@
     return ParseUrl(url, std::string(), std::string());
   }
 
+  bool ParseTurnUrl(const std::string& url) {
+    return ParseUrl(url, "username", "password");
+  }
+
   bool ParseUrl(const std::string& url,
                 const std::string& username,
                 const std::string& password) {
@@ -2640,7 +2644,8 @@
     server.password = password;
     server.tls_cert_policy = tls_certificate_policy;
     servers.push_back(server);
-    return webrtc::ParseIceServers(servers, &stun_servers_, &turn_servers_);
+    return webrtc::ParseIceServers(servers, &stun_servers_, &turn_servers_) ==
+           webrtc::RTCErrorType::NONE;
   }
 
  protected:
@@ -2660,13 +2665,13 @@
   EXPECT_EQ(0U, turn_servers_.size());
   stun_servers_.clear();
 
-  EXPECT_TRUE(ParseUrl("turn:hostname"));
+  EXPECT_TRUE(ParseTurnUrl("turn:hostname"));
   EXPECT_EQ(0U, stun_servers_.size());
   EXPECT_EQ(1U, turn_servers_.size());
   EXPECT_EQ(cricket::PROTO_UDP, turn_servers_[0].ports[0].proto);
   turn_servers_.clear();
 
-  EXPECT_TRUE(ParseUrl("turns:hostname"));
+  EXPECT_TRUE(ParseTurnUrl("turns:hostname"));
   EXPECT_EQ(0U, stun_servers_.size());
   EXPECT_EQ(1U, turn_servers_.size());
   EXPECT_EQ(cricket::PROTO_TLS, turn_servers_[0].ports[0].proto);
@@ -2675,7 +2680,7 @@
   turn_servers_.clear();
 
   EXPECT_TRUE(ParseUrl(
-      "turns:hostname", "", "",
+      "turns:hostname", "username", "password",
       PeerConnectionInterface::TlsCertPolicy::kTlsCertPolicyInsecureNoCheck));
   EXPECT_EQ(0U, stun_servers_.size());
   EXPECT_EQ(1U, turn_servers_.size());
@@ -2693,14 +2698,14 @@
 
 TEST_F(IceServerParsingTest, VerifyDefaults) {
   // TURNS defaults
-  EXPECT_TRUE(ParseUrl("turns:hostname"));
+  EXPECT_TRUE(ParseTurnUrl("turns:hostname"));
   EXPECT_EQ(1U, turn_servers_.size());
   EXPECT_EQ(5349, turn_servers_[0].ports[0].address.port());
   EXPECT_EQ(cricket::PROTO_TLS, turn_servers_[0].ports[0].proto);
   turn_servers_.clear();
 
   // TURN defaults
-  EXPECT_TRUE(ParseUrl("turn:hostname"));
+  EXPECT_TRUE(ParseTurnUrl("turn:hostname"));
   EXPECT_EQ(1U, turn_servers_.size());
   EXPECT_EQ(3478, turn_servers_[0].ports[0].address.port());
   EXPECT_EQ(cricket::PROTO_UDP, turn_servers_[0].ports[0].proto);
@@ -2765,33 +2770,33 @@
 
 // Test parsing the "?transport=xxx" part of the URL.
 TEST_F(IceServerParsingTest, ParseTransport) {
-  EXPECT_TRUE(ParseUrl("turn:hostname:1234?transport=tcp"));
+  EXPECT_TRUE(ParseTurnUrl("turn:hostname:1234?transport=tcp"));
   EXPECT_EQ(1U, turn_servers_.size());
   EXPECT_EQ(cricket::PROTO_TCP, turn_servers_[0].ports[0].proto);
   turn_servers_.clear();
 
-  EXPECT_TRUE(ParseUrl("turn:hostname?transport=udp"));
+  EXPECT_TRUE(ParseTurnUrl("turn:hostname?transport=udp"));
   EXPECT_EQ(1U, turn_servers_.size());
   EXPECT_EQ(cricket::PROTO_UDP, turn_servers_[0].ports[0].proto);
   turn_servers_.clear();
 
-  EXPECT_FALSE(ParseUrl("turn:hostname?transport=invalid"));
-  EXPECT_FALSE(ParseUrl("turn:hostname?transport="));
-  EXPECT_FALSE(ParseUrl("turn:hostname?="));
-  EXPECT_FALSE(ParseUrl("?"));
+  EXPECT_FALSE(ParseTurnUrl("turn:hostname?transport=invalid"));
+  EXPECT_FALSE(ParseTurnUrl("turn:hostname?transport="));
+  EXPECT_FALSE(ParseTurnUrl("turn:hostname?="));
+  EXPECT_FALSE(ParseTurnUrl("?"));
 }
 
 // Test parsing ICE username contained in URL.
 TEST_F(IceServerParsingTest, ParseUsername) {
-  EXPECT_TRUE(ParseUrl("turn:user@hostname"));
+  EXPECT_TRUE(ParseTurnUrl("turn:user@hostname"));
   EXPECT_EQ(1U, turn_servers_.size());
   EXPECT_EQ("user", turn_servers_[0].credentials.username);
   turn_servers_.clear();
 
-  EXPECT_FALSE(ParseUrl("turn:@hostname"));
-  EXPECT_FALSE(ParseUrl("turn:username@"));
-  EXPECT_FALSE(ParseUrl("turn:@"));
-  EXPECT_FALSE(ParseUrl("turn:user@name@hostname"));
+  EXPECT_FALSE(ParseTurnUrl("turn:@hostname"));
+  EXPECT_FALSE(ParseTurnUrl("turn:username@"));
+  EXPECT_FALSE(ParseTurnUrl("turn:@"));
+  EXPECT_FALSE(ParseTurnUrl("turn:user@name@hostname"));
 }
 
 // Test that username and password from IceServer is copied into the resulting
@@ -2809,8 +2814,11 @@
   PeerConnectionInterface::IceServer server;
   server.urls.push_back("stun:hostname");
   server.urls.push_back("turn:hostname");
+  server.username = "foo";
+  server.password = "bar";
   servers.push_back(server);
-  EXPECT_TRUE(webrtc::ParseIceServers(servers, &stun_servers_, &turn_servers_));
+  EXPECT_EQ(webrtc::RTCErrorType::NONE,
+            webrtc::ParseIceServers(servers, &stun_servers_, &turn_servers_));
   EXPECT_EQ(1U, stun_servers_.size());
   EXPECT_EQ(1U, turn_servers_.size());
 }
@@ -2822,8 +2830,11 @@
   PeerConnectionInterface::IceServer server;
   server.urls.push_back("turn:hostname");
   server.urls.push_back("turn:hostname2");
+  server.username = "foo";
+  server.password = "bar";
   servers.push_back(server);
-  EXPECT_TRUE(webrtc::ParseIceServers(servers, &stun_servers_, &turn_servers_));
+  EXPECT_EQ(webrtc::RTCErrorType::NONE,
+            webrtc::ParseIceServers(servers, &stun_servers_, &turn_servers_));
   EXPECT_EQ(2U, turn_servers_.size());
   EXPECT_NE(turn_servers_[0].priority, turn_servers_[1].priority);
 }
diff --git a/webrtc/api/peerconnectioninterface.h b/webrtc/api/peerconnectioninterface.h
index 5f5a58b4..5e1fd32 100644
--- a/webrtc/api/peerconnectioninterface.h
+++ b/webrtc/api/peerconnectioninterface.h
@@ -150,9 +150,10 @@
 typedef MetricsObserverInterface UMAObserver;
 
 // Enumeration to represent distinct classes of errors that an application
-// may wish to act upon differently. These roughly map to DOMExceptions in
-// the web API, as described in the comments below.
-enum class RtcError {
+// may wish to act upon differently. These roughly map to DOMExceptions or
+// RTCError "errorDetailEnum" values in the web API, as described in the
+// comments below.
+enum class RTCErrorType {
   // No error.
   NONE,
   // A supplied parameter is valid, but currently unsupported.
@@ -183,9 +184,26 @@
   INTERNAL_ERROR,
 };
 
+// Roughly corresponds to RTCError in the web api. Holds an error type and
+// possibly additional information specific to that error.
+//
+// Doesn't contain anything beyond a type now, but will in the future as more
+// errors are implemented.
+class RTCError {
+ public:
+  RTCError() : type_(RTCErrorType::NONE) {}
+  explicit RTCError(RTCErrorType type) : type_(type) {}
+
+  RTCErrorType type() const { return type_; }
+  void set_type(RTCErrorType type) { type_ = type; }
+
+ private:
+  RTCErrorType type_;
+};
+
 // Outputs the error as a friendly string.
 // Update this method when adding a new error type.
-std::ostream& operator<<(std::ostream& stream, RtcError error);
+std::ostream& operator<<(std::ostream& stream, RTCErrorType error);
 
 class PeerConnectionInterface : public rtc::RefCountInterface {
  public:
@@ -319,6 +337,9 @@
       }
     }
 
+    bool operator==(const RTCConfiguration& o) const;
+    bool operator!=(const RTCConfiguration& o) const;
+
     bool dscp() { return media_config.enable_dscp; }
     void set_dscp(bool enable) { media_config.enable_dscp = enable; }
 
@@ -392,6 +413,9 @@
     // If true, ICE role is redetermined when peerconnection sets a local
     // transport description that indicates an ICE restart.
     bool redetermine_role_on_ice_restart = true;
+    //
+    // Don't forget to update operator== if adding something.
+    //
   };
 
   struct RTCOfferAnswerOptions {
@@ -569,14 +593,38 @@
   virtual PeerConnectionInterface::RTCConfiguration GetConfiguration() {
     return PeerConnectionInterface::RTCConfiguration();
   }
+
   // Sets the PeerConnection's global configuration to |config|.
+  //
+  // The members of |config| that may be changed are |type|, |servers|,
+  // |ice_candidate_pool_size| and |prune_turn_ports| (though the candidate
+  // pool size can't be changed after the first call to SetLocalDescription).
+  // Note that this means the BUNDLE and RTCP-multiplexing policies cannot be
+  // changed with this method.
+  //
   // Any changes to STUN/TURN servers or ICE candidate policy will affect the
   // next gathering phase, and cause the next call to createOffer to generate
-  // new ICE credentials. Note that the BUNDLE and RTCP-multiplexing policies
-  // cannot be changed with this method.
+  // new ICE credentials, as described in JSEP. This also occurs when
+  // |prune_turn_ports| changes, for the same reasoning.
+  //
+  // If an error occurs, returns false and populates |error| if non-null:
+  // - INVALID_MODIFICATION if |config| contains a modified parameter other
+  //   than one of the parameters listed above.
+  // - INVALID_RANGE if |ice_candidate_pool_size| is out of range.
+  // - SYNTAX_ERROR if parsing an ICE server URL failed.
+  // - INVALID_PARAMETER if a TURN server is missing |username| or |password|.
+  // - INTERNAL_ERROR if an unexpected error occurred.
+  //
   // TODO(deadbeef): Make this pure virtual once all Chrome subclasses of
   // PeerConnectionInterface implement it.
   virtual bool SetConfiguration(
+      const PeerConnectionInterface::RTCConfiguration& config,
+      RTCError* error) {
+    return false;
+  }
+  // Version without error output param for backwards compatibility.
+  // TODO(deadbeef): Remove once chromium is updated.
+  virtual bool SetConfiguration(
       const PeerConnectionInterface::RTCConfiguration& config) {
     return false;
   }
diff --git a/webrtc/api/peerconnectioninterface_unittest.cc b/webrtc/api/peerconnectioninterface_unittest.cc
index d6da24e..2da3755 100644
--- a/webrtc/api/peerconnectioninterface_unittest.cc
+++ b/webrtc/api/peerconnectioninterface_unittest.cc
@@ -321,6 +321,8 @@
 using webrtc::ObserverInterface;
 using webrtc::PeerConnectionInterface;
 using webrtc::PeerConnectionObserver;
+using webrtc::RTCError;
+using webrtc::RTCErrorType;
 using webrtc::RtpReceiverInterface;
 using webrtc::RtpSenderInterface;
 using webrtc::SdpParseError;
@@ -694,6 +696,17 @@
     CreatePeerConnection(PeerConnectionInterface::RTCConfiguration(), nullptr);
   }
 
+  // DTLS does not work in a loopback call, so is disabled for most of the
+  // tests in this file.
+  void CreatePeerConnectionWithoutDtls() {
+    FakeConstraints no_dtls_constraints;
+    no_dtls_constraints.AddMandatory(
+        webrtc::MediaConstraintsInterface::kEnableDtlsSrtp, false);
+
+    CreatePeerConnection(PeerConnectionInterface::RTCConfiguration(),
+                         &no_dtls_constraints);
+  }
+
   void CreatePeerConnection(webrtc::MediaConstraintsInterface* constraints) {
     CreatePeerConnection(PeerConnectionInterface::RTCConfiguration(),
                          constraints);
@@ -722,17 +735,6 @@
         new cricket::FakePortAllocator(rtc::Thread::Current(), nullptr));
     port_allocator_ = port_allocator.get();
 
-    // DTLS does not work in a loopback call, so is disabled for most of the
-    // tests in this file. We only create a FakeIdentityService if the test
-    // explicitly sets the constraint.
-    FakeConstraints default_constraints;
-    if (!constraints) {
-      constraints = &default_constraints;
-
-      default_constraints.AddMandatory(
-          webrtc::MediaConstraintsInterface::kEnableDtlsSrtp, false);
-    }
-
     std::unique_ptr<rtc::RTCCertificateGeneratorInterface> cert_generator;
     bool dtls;
     if (FindConstraint(constraints,
@@ -898,7 +900,7 @@
   }
 
   void InitiateCall() {
-    CreatePeerConnection();
+    CreatePeerConnectionWithoutDtls();
     // Create a local stream with audio&video tracks.
     AddAudioVideoStream(kStreamLabel1, "audio_label", "video_label");
     CreateOfferReceiveAnswer();
@@ -1105,7 +1107,7 @@
   }
 
   std::unique_ptr<SessionDescriptionInterface> CreateOfferWithOneAudioStream() {
-    CreatePeerConnection();
+    CreatePeerConnectionWithoutDtls();
     AddVoiceStream(kStreamLabel1);
     std::unique_ptr<SessionDescriptionInterface> offer;
     EXPECT_TRUE(DoCreateOffer(&offer, nullptr));
@@ -1281,7 +1283,7 @@
 }
 
 TEST_F(PeerConnectionInterfaceTest, AddStreams) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   AddVideoStream(kStreamLabel1);
   AddVoiceStream(kStreamLabel2);
   ASSERT_EQ(2u, pc_->local_streams()->count());
@@ -1311,7 +1313,7 @@
 
 // Test that the created offer includes streams we added.
 TEST_F(PeerConnectionInterfaceTest, AddedStreamsPresentInOffer) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   AddAudioVideoStream(kStreamLabel1, "audio_track", "video_track");
   std::unique_ptr<SessionDescriptionInterface> offer;
   ASSERT_TRUE(DoCreateOffer(&offer, nullptr));
@@ -1355,7 +1357,7 @@
 }
 
 TEST_F(PeerConnectionInterfaceTest, RemoveStream) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   AddVideoStream(kStreamLabel1);
   ASSERT_EQ(1u, pc_->local_streams()->count());
   pc_->RemoveStream(pc_->local_streams()->at(0));
@@ -1367,7 +1369,7 @@
 // and that the RtpSenders are created correctly.
 // Also tests that RemoveTrack removes the tracks from subsequent offers.
 TEST_F(PeerConnectionInterfaceTest, AddTrackRemoveTrack) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   // Create a dummy stream, so tracks share a stream label.
   rtc::scoped_refptr<MediaStreamInterface> stream(
       pc_factory_->CreateLocalMediaStream(kStreamLabel1));
@@ -1442,7 +1444,7 @@
 // Test creating senders without a stream specified,
 // expecting a random stream ID to be generated.
 TEST_F(PeerConnectionInterfaceTest, AddTrackWithoutStream) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   // Create a dummy stream, so tracks share a stream label.
   rtc::scoped_refptr<AudioTrackInterface> audio_track(
       pc_factory_->CreateAudioTrack("audio_track", nullptr));
@@ -1470,7 +1472,7 @@
 }
 
 TEST_F(PeerConnectionInterfaceTest, CreateOfferReceivePrAnswerAndAnswer) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   AddVideoStream(kStreamLabel1);
   CreateOfferAsLocalDescription();
   std::string offer;
@@ -1480,7 +1482,7 @@
 }
 
 TEST_F(PeerConnectionInterfaceTest, ReceiveOfferCreateAnswer) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   AddVideoStream(kStreamLabel1);
 
   CreateOfferAsRemoteDescription();
@@ -1490,7 +1492,7 @@
 }
 
 TEST_F(PeerConnectionInterfaceTest, ReceiveOfferCreatePrAnswerAndAnswer) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   AddVideoStream(kStreamLabel1);
 
   CreateOfferAsRemoteDescription();
@@ -1513,7 +1515,7 @@
 // Tests that after negotiating an audio only call, the respondent can perform a
 // renegotiation that removes the audio stream.
 TEST_F(PeerConnectionInterfaceTest, RenegotiateAudioOnly) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   AddVoiceStream(kStreamLabel1);
   CreateOfferAsRemoteDescription();
   CreateAnswerAsLocalDescription();
@@ -1526,7 +1528,7 @@
 
 // Test that candidates are generated and that we can parse our own candidates.
 TEST_F(PeerConnectionInterfaceTest, IceCandidates) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
 
   EXPECT_FALSE(pc_->AddIceCandidate(observer_.last_candidate_.get()));
   // SetRemoteDescription takes ownership of offer.
@@ -1549,7 +1551,7 @@
 // Test that CreateOffer and CreateAnswer will fail if the track labels are
 // not unique.
 TEST_F(PeerConnectionInterfaceTest, CreateOfferAnswerWithInvalidStream) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   // Create a regular offer for the CreateAnswer test later.
   std::unique_ptr<SessionDescriptionInterface> offer;
   EXPECT_TRUE(DoCreateOffer(&offer, nullptr));
@@ -1570,7 +1572,7 @@
 // Test that we will get different SSRCs for each tracks in the offer and answer
 // we created.
 TEST_F(PeerConnectionInterfaceTest, SsrcInOfferAnswer) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   // Create a local stream with audio&video tracks having different labels.
   AddAudioVideoStream(kStreamLabel1, "audio_label", "video_label");
 
@@ -1602,7 +1604,7 @@
 // the stream to a PeerConnection.
 // TODO(deadbeef): Remove this test once this behavior is no longer supported.
 TEST_F(PeerConnectionInterfaceTest, AddTrackAfterAddStream) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   // Create audio stream and add to PeerConnection.
   AddVoiceStream(kStreamLabel1);
   MediaStreamInterface* stream = pc_->local_streams()->at(0);
@@ -1626,7 +1628,7 @@
 // the stream to a PeerConnection.
 // TODO(deadbeef): Remove this test once this behavior is no longer supported.
 TEST_F(PeerConnectionInterfaceTest, RemoveTrackAfterAddStream) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   // Create audio/video stream and add to PeerConnection.
   AddAudioVideoStream(kStreamLabel1, "audio_label", "video_label");
   MediaStreamInterface* stream = pc_->local_streams()->at(0);
@@ -1645,7 +1647,7 @@
 // Test creating a sender with a stream ID, and ensure the ID is populated
 // in the offer.
 TEST_F(PeerConnectionInterfaceTest, CreateSenderWithStream) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   pc_->CreateSender("video", kStreamLabel1);
 
   std::unique_ptr<SessionDescriptionInterface> offer;
@@ -2075,7 +2077,7 @@
 // limited set of audio codecs and receive an updated offer with more audio
 // codecs, where the added codecs are not supported.
 TEST_F(PeerConnectionInterfaceTest, ReceiveUpdatedAudioOfferWithBadCodecs) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   AddVoiceStream("audio_label");
   CreateOfferAsLocalDescription();
 
@@ -2183,6 +2185,17 @@
   EXPECT_EQ(cricket::CF_RELAY, port_allocator_->candidate_filter());
 }
 
+TEST_F(PeerConnectionInterfaceTest, SetConfigurationChangesPruneTurnPortsFlag) {
+  PeerConnectionInterface::RTCConfiguration config;
+  config.prune_turn_ports = false;
+  CreatePeerConnection(config, nullptr);
+  EXPECT_FALSE(port_allocator_->prune_turn_ports());
+
+  config.prune_turn_ports = true;
+  EXPECT_TRUE(pc_->SetConfiguration(config));
+  EXPECT_TRUE(port_allocator_->prune_turn_ports());
+}
+
 // Test that when SetConfiguration changes both the pool size and other
 // attributes, the pooled session is created with the updated attributes.
 TEST_F(PeerConnectionInterfaceTest,
@@ -2203,7 +2216,8 @@
   EXPECT_EQ(1UL, session->stun_servers().size());
 }
 
-// Test that after SetLocalDescription, changing the pool size is not allowed.
+// Test that after SetLocalDescription, changing the pool size is not allowed,
+// and an invalid modification error is returned.
 TEST_F(PeerConnectionInterfaceTest,
        CantChangePoolSizeAfterSetLocalDescription) {
   CreatePeerConnection();
@@ -2220,7 +2234,91 @@
   // Set local answer; now it's too late.
   CreateAnswerAsLocalDescription();
   config.ice_candidate_pool_size = 3;
-  EXPECT_FALSE(pc_->SetConfiguration(config));
+  RTCError error;
+  EXPECT_FALSE(pc_->SetConfiguration(config, &error));
+  EXPECT_EQ(RTCErrorType::INVALID_MODIFICATION, error.type());
+}
+
+// Test that SetConfiguration returns an invalid modification error if
+// modifying a field in the configuration that isn't allowed to be modified.
+TEST_F(PeerConnectionInterfaceTest,
+       SetConfigurationReturnsInvalidModificationError) {
+  PeerConnectionInterface::RTCConfiguration config;
+  config.bundle_policy = PeerConnectionInterface::kBundlePolicyBalanced;
+  config.rtcp_mux_policy = PeerConnectionInterface::kRtcpMuxPolicyNegotiate;
+  config.continual_gathering_policy = PeerConnectionInterface::GATHER_ONCE;
+  CreatePeerConnection(config, nullptr);
+
+  PeerConnectionInterface::RTCConfiguration modified_config = config;
+  modified_config.bundle_policy =
+      PeerConnectionInterface::kBundlePolicyMaxBundle;
+  RTCError error;
+  EXPECT_FALSE(pc_->SetConfiguration(modified_config, &error));
+  EXPECT_EQ(RTCErrorType::INVALID_MODIFICATION, error.type());
+
+  modified_config = config;
+  modified_config.rtcp_mux_policy =
+      PeerConnectionInterface::kRtcpMuxPolicyRequire;
+  error.set_type(RTCErrorType::NONE);
+  EXPECT_FALSE(pc_->SetConfiguration(modified_config, &error));
+  EXPECT_EQ(RTCErrorType::INVALID_MODIFICATION, error.type());
+
+  modified_config = config;
+  modified_config.continual_gathering_policy =
+      PeerConnectionInterface::GATHER_CONTINUALLY;
+  error.set_type(RTCErrorType::NONE);
+  EXPECT_FALSE(pc_->SetConfiguration(modified_config, &error));
+  EXPECT_EQ(RTCErrorType::INVALID_MODIFICATION, error.type());
+}
+
+// Test that SetConfiguration returns a range error if the candidate pool size
+// is negative or larger than allowed by the spec.
+TEST_F(PeerConnectionInterfaceTest,
+       SetConfigurationReturnsRangeErrorForBadCandidatePoolSize) {
+  PeerConnectionInterface::RTCConfiguration config;
+  CreatePeerConnection(config, nullptr);
+
+  config.ice_candidate_pool_size = -1;
+  RTCError error;
+  EXPECT_FALSE(pc_->SetConfiguration(config, &error));
+  EXPECT_EQ(RTCErrorType::INVALID_RANGE, error.type());
+
+  config.ice_candidate_pool_size = INT_MAX;
+  error.set_type(RTCErrorType::NONE);
+  EXPECT_FALSE(pc_->SetConfiguration(config, &error));
+  EXPECT_EQ(RTCErrorType::INVALID_RANGE, error.type());
+}
+
+// Test that SetConfiguration returns a syntax error if parsing an ICE server
+// URL failed.
+TEST_F(PeerConnectionInterfaceTest,
+       SetConfigurationReturnsSyntaxErrorFromBadIceUrls) {
+  PeerConnectionInterface::RTCConfiguration config;
+  CreatePeerConnection(config, nullptr);
+
+  PeerConnectionInterface::IceServer bad_server;
+  bad_server.uri = "stunn:www.example.com";
+  config.servers.push_back(bad_server);
+  RTCError error;
+  EXPECT_FALSE(pc_->SetConfiguration(config, &error));
+  EXPECT_EQ(RTCErrorType::SYNTAX_ERROR, error.type());
+}
+
+// Test that SetConfiguration returns an invalid parameter error if a TURN
+// IceServer is missing a username or password.
+TEST_F(PeerConnectionInterfaceTest,
+       SetConfigurationReturnsInvalidParameterIfCredentialsMissing) {
+  PeerConnectionInterface::RTCConfiguration config;
+  CreatePeerConnection(config, nullptr);
+
+  PeerConnectionInterface::IceServer bad_server;
+  bad_server.uri = "turn:www.example.com";
+  // Missing password.
+  bad_server.username = "foo";
+  config.servers.push_back(bad_server);
+  RTCError error;
+  EXPECT_FALSE(pc_->SetConfiguration(config, &error));
+  EXPECT_EQ(RTCErrorType::INVALID_PARAMETER, error.type());
 }
 
 // Test that PeerConnection::Close changes the states to closed and all remote
@@ -2255,7 +2353,7 @@
 // Test that PeerConnection methods fails gracefully after
 // PeerConnection::Close has been called.
 TEST_F(PeerConnectionInterfaceTest, CloseAndTestMethods) {
-  CreatePeerConnection();
+  CreatePeerConnectionWithoutDtls();
   AddAudioVideoStream(kStreamLabel1, "audio_label", "video_label");
   CreateOfferAsRemoteDescription();
   CreateAnswerAsLocalDescription();
@@ -3227,10 +3325,41 @@
   EXPECT_TRUE(updated_answer_options.has_video());
 }
 
-TEST(RtcErrorTest, OstreamOperator) {
+TEST(RTCErrorTypeTest, OstreamOperator) {
   std::ostringstream oss;
-  oss << webrtc::RtcError::NONE << ' '
-      << webrtc::RtcError::INVALID_PARAMETER << ' '
-      << webrtc::RtcError::INTERNAL_ERROR;
+  oss << webrtc::RTCErrorType::NONE << ' '
+      << webrtc::RTCErrorType::INVALID_PARAMETER << ' '
+      << webrtc::RTCErrorType::INTERNAL_ERROR;
   EXPECT_EQ("NONE INVALID_PARAMETER INTERNAL_ERROR", oss.str());
 }
+
+// Tests a few random fields being different.
+TEST(RTCConfigurationTest, ComparisonOperators) {
+  PeerConnectionInterface::RTCConfiguration a;
+  PeerConnectionInterface::RTCConfiguration b;
+  EXPECT_EQ(a, b);
+
+  PeerConnectionInterface::RTCConfiguration c;
+  c.servers.push_back(PeerConnectionInterface::IceServer());
+  EXPECT_NE(a, c);
+
+  PeerConnectionInterface::RTCConfiguration d;
+  d.type = PeerConnectionInterface::kRelay;
+  EXPECT_NE(a, d);
+
+  PeerConnectionInterface::RTCConfiguration e;
+  e.audio_jitter_buffer_max_packets = 5;
+  EXPECT_NE(a, e);
+
+  PeerConnectionInterface::RTCConfiguration f;
+  f.ice_connection_receiving_timeout = 1337;
+  EXPECT_NE(a, f);
+
+  PeerConnectionInterface::RTCConfiguration g;
+  g.disable_ipv6 = true;
+  EXPECT_NE(a, g);
+
+  PeerConnectionInterface::RTCConfiguration h(
+      PeerConnectionInterface::RTCConfigurationType::kAggressive);
+  EXPECT_NE(a, h);
+}
diff --git a/webrtc/api/peerconnectionproxy.h b/webrtc/api/peerconnectionproxy.h
index 2110ee2..1609a75 100644
--- a/webrtc/api/peerconnectionproxy.h
+++ b/webrtc/api/peerconnectionproxy.h
@@ -72,6 +72,10 @@
   PROXY_METHOD2(void, SetRemoteDescription, SetSessionDescriptionObserver*,
                 SessionDescriptionInterface*)
   PROXY_METHOD0(PeerConnectionInterface::RTCConfiguration, GetConfiguration);
+  PROXY_METHOD2(bool,
+                SetConfiguration,
+                const PeerConnectionInterface::RTCConfiguration&,
+                RTCError*);
   PROXY_METHOD1(bool,
                 SetConfiguration,
                 const PeerConnectionInterface::RTCConfiguration&);