Revert "[Sheriff] Revert "[Perfect Negotiation] Surface session descriptions at the right time.""

This reverts commit 3dbd8ec2.

Reason for revert: I don't think this is the culprit and it looks like this test has been flaking for a couple of weeks, see:
https://analysis.chromium.org/p/chromium/flake-portal/flakes/occurrences?key=ag9zfmZpbmRpdC1mb3ItbWVyWAsSBUZsYWtlIk1jaHJvbWl1bUBibGlua193ZWJfdGVzdHNAZXh0ZXJuYWwvd3B0L3dlYnJ0Yy9wcm90b2NvbC9jcnlwdG8tc3VpdGUuaHR0cHMuaHRtbAw

More details here: https://bugs.chromium.org/p/chromium/issues/detail?id=1122106

Original change's description:
> [Sheriff] Revert "[Perfect Negotiation] Surface session descriptions at the right time."
> 
> This reverts commit 3bc91ccc.
> 
> Reason for revert: Failure of WebKit Linux ASAN build, and that's the suspect for root cause. See https://ci.chromium.org/p/chromium/builders/ci/WebKit%20Linux%20ASAN/17329
> 
> Original change's description:
> > [Perfect Negotiation] Surface session descriptions at the right time.
> > 
> > This fixes another timing related issue that blocks Perfect Negotiation.
> > 
> > Before this CL, current/pending local/remote description attributes do
> > blocking-invokes on the webrtc thread, fetching the most up-to-date
> > states. This can prematurely expose the result of "in-parallel"
> > operations that have not surfaced yet, such as:
> > - setLocalDescription
> > - setRemoteDescription
> > - addIceCandidate
> > 
> > This CL fixes that by copying the SDP states when any of these
> > operations complete on the WebRTC thread and carry them over in the
> > PostTask to the main thread. Here, we store these snapshots in
> > "internal slots" (variables living on the main thread). With this CL,
> > reading SDP attributes from RTCPeerConnection is non-blocking and
> > spec-compliant.
> > 
> > WPT test coverage added for the exact timing of SLD/SRD and other test
> > expectations are updated. addIceCandidate updating the SDP is already
> > covered by old WPTs.
> > 
> > Bug: chromium:1110347
> > Change-Id: Id41ec354465525c6cedf631fe2209fe097148f60
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2323359
> > Commit-Queue: Henrik Boström <hbos@chromium.org>
> > Reviewed-by: Harald Alvestrand <hta@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#801798}
> 
> TBR=hta@chromium.org,hbos@chromium.org
> 
> Change-Id: I4af12fd1430773ea3d134cfc37b9c5e736f20ed0
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: chromium:1110347
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2377715
> Reviewed-by: Amr Aboelkher <amraboelkher@google.com>
> Commit-Queue: Amr Aboelkher <amraboelkher@google.com>
> Cr-Commit-Position: refs/heads/master@{#801822}

TBR=hta@chromium.org,hbos@chromium.org,amraboelkher@google.com

Change-Id: Ia0f82e0d1b4660cf0d3641aaa446127092c6e6f7
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:1110347
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2379192Reviewed-by: Henrik Boström <hbos@chromium.org>
Commit-Queue: Henrik Boström <hbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#802114}

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

@@ -35,6 +35,11 @@ class MockRTCPeerConnectionHandlerClient
                     const String& url,
                     int error_code,
                     const String& error_text));
+  MOCK_METHOD4(DidChangeSessionDescriptions,
+               void(RTCSessionDescriptionPlatform*,
+                    RTCSessionDescriptionPlatform*,
+                    RTCSessionDescriptionPlatform*,
+                    RTCSessionDescriptionPlatform*));
   MOCK_METHOD1(DidChangeSignalingState,
                void(webrtc::PeerConnectionInterface::SignalingState state));
   MOCK_METHOD1(DidChangeIceGatheringState,

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

@@ -286,36 +286,6 @@ void MockRTCPeerConnectionHandlerPlatform::SetRemoteDescription(
     RTCVoidRequest*,
     RTCSessionDescriptionPlatform*) {}
 
-RTCSessionDescriptionPlatform*
-MockRTCPeerConnectionHandlerPlatform::LocalDescription() {
-  return nullptr;
-}
-
-RTCSessionDescriptionPlatform*
-MockRTCPeerConnectionHandlerPlatform::RemoteDescription() {
-  return nullptr;
-}
-
-RTCSessionDescriptionPlatform*
-MockRTCPeerConnectionHandlerPlatform::CurrentLocalDescription() {
-  return nullptr;
-}
-
-RTCSessionDescriptionPlatform*
-MockRTCPeerConnectionHandlerPlatform::CurrentRemoteDescription() {
-  return nullptr;
-}
-
-RTCSessionDescriptionPlatform*
-MockRTCPeerConnectionHandlerPlatform::PendingLocalDescription() {
-  return nullptr;
-}
-
-RTCSessionDescriptionPlatform*
-MockRTCPeerConnectionHandlerPlatform::PendingRemoteDescription() {
-  return nullptr;
-}
-
 const webrtc::PeerConnectionInterface::RTCConfiguration&
 MockRTCPeerConnectionHandlerPlatform::GetConfiguration() const {
   static const webrtc::PeerConnectionInterface::RTCConfiguration configuration;

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

@@ -48,12 +48,6 @@ class MockRTCPeerConnectionHandlerPlatform : public RTCPeerConnectionHandler {
                            RTCSessionDescriptionPlatform*) override;
   void SetRemoteDescription(RTCVoidRequest*,
                             RTCSessionDescriptionPlatform*) override;
-  RTCSessionDescriptionPlatform* LocalDescription() override;
-  RTCSessionDescriptionPlatform* RemoteDescription() override;
-  RTCSessionDescriptionPlatform* CurrentLocalDescription() override;
-  RTCSessionDescriptionPlatform* CurrentRemoteDescription() override;
-  RTCSessionDescriptionPlatform* PendingLocalDescription() override;
-  RTCSessionDescriptionPlatform* PendingRemoteDescription() override;
   const webrtc::PeerConnectionInterface::RTCConfiguration& GetConfiguration()
       const override;
   webrtc::RTCErrorType SetConfiguration(

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

@@ -746,6 +746,10 @@ RTCPeerConnection::RTCPeerConnection(
     MediaConstraints constraints,
     ExceptionState& exception_state)
     : ExecutionContextLifecycleObserver(context),
+      pending_local_description_(nullptr),
+      current_local_description_(nullptr),
+      pending_remote_description_(nullptr),
+      current_remote_description_(nullptr),
       signaling_state_(
           webrtc::PeerConnectionInterface::SignalingState::kStable),
       ice_gathering_state_(webrtc::PeerConnectionInterface::kIceGatheringNew),
@@ -1459,28 +1463,17 @@ ScriptPromise RTCPeerConnection::setLocalDescription(
   return ScriptPromise::CastUndefined(script_state);
 }
 
-RTCSessionDescription* RTCPeerConnection::localDescription() {
-  auto* platform_session_description = peer_handler_->LocalDescription();
-  if (!platform_session_description)
-    return nullptr;
-
-  return RTCSessionDescription::Create(platform_session_description);
+RTCSessionDescription* RTCPeerConnection::localDescription() const {
+  return pending_local_description_ ? pending_local_description_
+                                    : current_local_description_;
 }
 
-RTCSessionDescription* RTCPeerConnection::currentLocalDescription() {
-  auto* platform_session_description = peer_handler_->CurrentLocalDescription();
-  if (!platform_session_description)
-    return nullptr;
-
-  return RTCSessionDescription::Create(platform_session_description);
+RTCSessionDescription* RTCPeerConnection::currentLocalDescription() const {
+  return current_local_description_;
 }
 
-RTCSessionDescription* RTCPeerConnection::pendingLocalDescription() {
-  auto* platform_session_description = peer_handler_->PendingLocalDescription();
-  if (!platform_session_description)
-    return nullptr;
-
-  return RTCSessionDescription::Create(platform_session_description);
+RTCSessionDescription* RTCPeerConnection::pendingLocalDescription() const {
+  return pending_local_description_;
 }
 
 ScriptPromise RTCPeerConnection::setRemoteDescription(
@@ -1587,30 +1580,17 @@ ScriptPromise RTCPeerConnection::setRemoteDescription(
   return ScriptPromise::CastUndefined(script_state);
 }
 
-RTCSessionDescription* RTCPeerConnection::remoteDescription() {
-  auto* platform_session_description = peer_handler_->RemoteDescription();
-  if (!platform_session_description)
-    return nullptr;
-
-  return RTCSessionDescription::Create(platform_session_description);
+RTCSessionDescription* RTCPeerConnection::remoteDescription() const {
+  return pending_remote_description_ ? pending_remote_description_
+                                     : current_remote_description_;
 }
 
-RTCSessionDescription* RTCPeerConnection::currentRemoteDescription() {
-  auto* platform_session_description =
-      peer_handler_->CurrentRemoteDescription();
-  if (!platform_session_description)
-    return nullptr;
-
-  return RTCSessionDescription::Create(platform_session_description);
+RTCSessionDescription* RTCPeerConnection::currentRemoteDescription() const {
+  return current_remote_description_;
 }
 
-RTCSessionDescription* RTCPeerConnection::pendingRemoteDescription() {
-  auto* platform_session_description =
-      peer_handler_->PendingRemoteDescription();
-  if (!platform_session_description)
-    return nullptr;
-
-  return RTCSessionDescription::Create(platform_session_description);
+RTCSessionDescription* RTCPeerConnection::pendingRemoteDescription() const {
+  return pending_remote_description_;
 }
 
 RTCConfiguration* RTCPeerConnection::getConfiguration(
@@ -2034,7 +2014,7 @@ String RTCPeerConnection::connectionState() const {
 }
 
 base::Optional<bool> RTCPeerConnection::canTrickleIceCandidates() const {
-  if (closed_ || !peer_handler_->RemoteDescription()) {
+  if (closed_ || !remoteDescription()) {
     return base::nullopt;
   }
   webrtc::PeerConnectionInterface* native_connection =
@@ -2894,6 +2874,31 @@ void RTCPeerConnection::DidFailICECandidate(const String& address,
       address, port, host_candidate, url, error_code, error_text));
 }
 
+void RTCPeerConnection::DidChangeSessionDescriptions(
+    RTCSessionDescriptionPlatform* pending_local_description,
+    RTCSessionDescriptionPlatform* current_local_description,
+    RTCSessionDescriptionPlatform* pending_remote_description,
+    RTCSessionDescriptionPlatform* current_remote_description) {
+  DCHECK(!closed_);
+  DCHECK(GetExecutionContext()->IsContextThread());
+  pending_local_description_ =
+      pending_local_description
+          ? RTCSessionDescription::Create(pending_local_description)
+          : nullptr;
+  current_local_description_ =
+      current_local_description
+          ? RTCSessionDescription::Create(current_local_description)
+          : nullptr;
+  pending_remote_description_ =
+      pending_remote_description
+          ? RTCSessionDescription::Create(pending_remote_description)
+          : nullptr;
+  current_remote_description_ =
+      current_remote_description
+          ? RTCSessionDescription::Create(current_remote_description)
+          : nullptr;
+}
+
 void RTCPeerConnection::DidChangeSignalingState(
     webrtc::PeerConnectionInterface::SignalingState new_state) {
   DCHECK(!closed_);
@@ -3545,6 +3550,10 @@ void RTCPeerConnection::DispatchScheduledEvents() {
 }
 
 void RTCPeerConnection::Trace(Visitor* visitor) const {
+  visitor->Trace(pending_local_description_);
+  visitor->Trace(current_local_description_);
+  visitor->Trace(pending_remote_description_);
+  visitor->Trace(current_remote_description_);
   visitor->Trace(tracks_);
   visitor->Trace(rtp_senders_);
   visitor->Trace(rtp_receivers_);

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

@@ -183,9 +183,9 @@ class MODULES_EXPORT RTCPeerConnection final
       const RTCSessionDescriptionInit*,
       V8VoidFunction*,
       V8RTCPeerConnectionErrorCallback* = nullptr);
-  RTCSessionDescription* localDescription();
-  RTCSessionDescription* currentLocalDescription();
-  RTCSessionDescription* pendingLocalDescription();
+  RTCSessionDescription* localDescription() const;
+  RTCSessionDescription* currentLocalDescription() const;
+  RTCSessionDescription* pendingLocalDescription() const;
 
   ScriptPromise setRemoteDescription(ScriptState*,
                                      const RTCSessionDescriptionInit*,
@@ -195,9 +195,9 @@ class MODULES_EXPORT RTCPeerConnection final
       const RTCSessionDescriptionInit*,
       V8VoidFunction*,
       V8RTCPeerConnectionErrorCallback* = nullptr);
-  RTCSessionDescription* remoteDescription();
-  RTCSessionDescription* currentRemoteDescription();
-  RTCSessionDescription* pendingRemoteDescription();
+  RTCSessionDescription* remoteDescription() const;
+  RTCSessionDescription* currentRemoteDescription() const;
+  RTCSessionDescription* pendingRemoteDescription() const;
 
   String signalingState() const;
 
@@ -337,6 +337,11 @@ class MODULES_EXPORT RTCPeerConnection final
                            const String& url,
                            int error_code,
                            const String& error_text) override;
+  void DidChangeSessionDescriptions(
+      RTCSessionDescriptionPlatform* pending_local_description,
+      RTCSessionDescriptionPlatform* current_local_description,
+      RTCSessionDescriptionPlatform* pending_remote_description,
+      RTCSessionDescriptionPlatform* current_remote_description) override;
   void DidChangeSignalingState(
       webrtc::PeerConnectionInterface::SignalingState) override;
   void DidChangeIceGatheringState(
@@ -571,6 +576,10 @@ class MODULES_EXPORT RTCPeerConnection final
 
   HeapHashSet<Member<RTCIceTransport>> ActiveIceTransports() const;
 
+  Member<RTCSessionDescription> pending_local_description_;
+  Member<RTCSessionDescription> current_local_description_;
+  Member<RTCSessionDescription> pending_remote_description_;
+  Member<RTCSessionDescription> current_remote_description_;
   webrtc::PeerConnectionInterface::SignalingState signaling_state_;
   webrtc::PeerConnectionInterface::IceGatheringState ice_gathering_state_;
   webrtc::PeerConnectionInterface::IceConnectionState ice_connection_state_;

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

@@ -154,13 +154,6 @@ class MODULES_EXPORT RTCPeerConnectionHandler {
   virtual void SetRemoteDescription(blink::RTCVoidRequest* request,
                                     RTCSessionDescriptionPlatform* description);
 
-  virtual RTCSessionDescriptionPlatform* LocalDescription();
-  virtual RTCSessionDescriptionPlatform* RemoteDescription();
-  virtual RTCSessionDescriptionPlatform* CurrentLocalDescription();
-  virtual RTCSessionDescriptionPlatform* CurrentRemoteDescription();
-  virtual RTCSessionDescriptionPlatform* PendingLocalDescription();
-  virtual RTCSessionDescriptionPlatform* PendingRemoteDescription();
-
   virtual const webrtc::PeerConnectionInterface::RTCConfiguration&
   GetConfiguration() const;
   virtual webrtc::RTCErrorType SetConfiguration(
@@ -259,6 +252,15 @@ class MODULES_EXPORT RTCPeerConnectionHandler {
   class SetLocalDescriptionRequest;
   friend class SetLocalDescriptionRequest;
 
+  void OnSessionDescriptionsUpdated(
+      std::unique_ptr<webrtc::SessionDescriptionInterface>
+          pending_local_description,
+      std::unique_ptr<webrtc::SessionDescriptionInterface>
+          current_local_description,
+      std::unique_ptr<webrtc::SessionDescriptionInterface>
+          pending_remote_description,
+      std::unique_ptr<webrtc::SessionDescriptionInterface>
+          current_remote_description);
   void OnSignalingChange(
       webrtc::PeerConnectionInterface::SignalingState new_state);
   void OnIceConnectionChange(

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

@@ -676,8 +676,6 @@ TEST_F(RTCPeerConnectionHandlerTest, setLocalDescription) {
 
   pc_handler_->SetLocalDescription(nullptr /*RTCVoidRequest*/, description);
   RunMessageLoopsUntilIdle();
-  EXPECT_EQ(description->GetType(), pc_handler_->LocalDescription()->GetType());
-  EXPECT_EQ(description->Sdp(), pc_handler_->LocalDescription()->Sdp());
 
   std::string sdp_string;
   ASSERT_TRUE(mock_peer_connection_->local_description());
@@ -711,8 +709,6 @@ TEST_F(RTCPeerConnectionHandlerTest, setLocalDescriptionParseError) {
   mock_dependency_factory_->SetFailToCreateSessionDescription(true);
   pc_handler_->SetLocalDescription(nullptr /*RTCVoidRequest*/, description);
   RunMessageLoopsUntilIdle();
-  // A description that failed to be applied shouldn't be stored.
-  EXPECT_TRUE(!pc_handler_->LocalDescription());
 }
 
 TEST_F(RTCPeerConnectionHandlerTest, setRemoteDescription) {
@@ -730,9 +726,6 @@ TEST_F(RTCPeerConnectionHandlerTest, setRemoteDescription) {
 
   pc_handler_->SetRemoteDescription(nullptr /*RTCVoidRequest*/, description);
   RunMessageLoopsUntilIdle();
-  EXPECT_EQ(description->GetType(),
-            pc_handler_->RemoteDescription()->GetType());
-  EXPECT_EQ(description->Sdp(), pc_handler_->RemoteDescription()->Sdp());
 
   std::string sdp_string;
   ASSERT_TRUE(mock_peer_connection_->remote_description());
@@ -766,8 +759,6 @@ TEST_F(RTCPeerConnectionHandlerTest, setRemoteDescriptionParseError) {
   mock_dependency_factory_->SetFailToCreateSessionDescription(true);
   pc_handler_->SetRemoteDescription(nullptr /*RTCVoidRequest*/, description);
   RunMessageLoopsUntilIdle();
-  // A description that failed to be applied shouldn't be stored.
-  EXPECT_TRUE(!pc_handler_->RemoteDescription());
 }
 
 TEST_F(RTCPeerConnectionHandlerTest, setConfiguration) {

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

@@ -6,10 +6,19 @@
 
 #include "base/bind.h"
 #include "base/check.h"
-#include "third_party/webrtc/pc/sdp_utils.h"
 
 namespace blink {
 
+std::unique_ptr<webrtc::SessionDescriptionInterface> CopySessionDescription(
+    const webrtc::SessionDescriptionInterface* description) {
+  if (!description)
+    return nullptr;
+  std::string sdp;
+  description->ToString(&sdp);
+  return std::unique_ptr<webrtc::SessionDescriptionInterface>(
+      webrtc::CreateSessionDescription(description->type(), sdp, nullptr));
+}
+
 WebRtcSetDescriptionObserver::States::States()
     : signaling_state(
           webrtc::PeerConnectionInterface::SignalingState::kClosed) {}
@@ -19,7 +28,9 @@ WebRtcSetDescriptionObserver::States::States(States&& other)
       sctp_transport_state(std::move(other.sctp_transport_state)),
       transceiver_states(std::move(other.transceiver_states)),
       pending_local_description(std::move(other.pending_local_description)),
-      current_local_description(std::move(other.current_local_description)) {}
+      current_local_description(std::move(other.current_local_description)),
+      pending_remote_description(std::move(other.pending_remote_description)),
+      current_remote_description(std::move(other.current_remote_description)) {}
 
 WebRtcSetDescriptionObserver::States::~States() = default;
 
@@ -30,6 +41,8 @@ operator=(States&& other) {
   transceiver_states = std::move(other.transceiver_states);
   pending_local_description = std::move(other.pending_local_description);
   current_local_description = std::move(other.current_local_description);
+  pending_remote_description = std::move(other.pending_remote_description);
+  current_remote_description = std::move(other.current_remote_description);
   return *this;
 }
 
@@ -81,22 +94,26 @@ void WebRtcSetDescriptionObserverHandlerImpl::OnSetDescriptionComplete(
   transceiver_state_surfacer.Initialize(pc_, track_adapter_map_,
                                         std::move(transceivers));
   std::unique_ptr<webrtc::SessionDescriptionInterface>
-      pending_local_description = pc_->pending_local_description()
-                                      ? webrtc::CloneSessionDescription(
-                                            pc_->pending_local_description())
-                                      : nullptr;
+      pending_local_description =
+          CopySessionDescription(pc_->pending_local_description());
+  std::unique_ptr<webrtc::SessionDescriptionInterface>
+      current_local_description =
+          CopySessionDescription(pc_->current_local_description());
   std::unique_ptr<webrtc::SessionDescriptionInterface>
-      current_local_description = pc_->current_local_description()
-                                      ? webrtc::CloneSessionDescription(
-                                            pc_->current_local_description())
-                                      : nullptr;
+      pending_remote_description =
+          CopySessionDescription(pc_->pending_remote_description());
+  std::unique_ptr<webrtc::SessionDescriptionInterface>
+      current_remote_description =
+          CopySessionDescription(pc_->current_remote_description());
   main_task_runner_->PostTask(
       FROM_HERE, base::BindOnce(&WebRtcSetDescriptionObserverHandlerImpl::
                                     OnSetDescriptionCompleteOnMainThread,
                                 this, std::move(error), pc_->signaling_state(),
                                 std::move(transceiver_state_surfacer),
                                 std::move(pending_local_description),
-                                std::move(current_local_description)));
+                                std::move(current_local_description),
+                                std::move(pending_remote_description),
+                                std::move(current_remote_description)));
 }
 
 void WebRtcSetDescriptionObserverHandlerImpl::
@@ -107,7 +124,11 @@ void WebRtcSetDescriptionObserverHandlerImpl::
         std::unique_ptr<webrtc::SessionDescriptionInterface>
             pending_local_description,
         std::unique_ptr<webrtc::SessionDescriptionInterface>
-            current_local_description) {
+            current_local_description,
+        std::unique_ptr<webrtc::SessionDescriptionInterface>
+            pending_remote_description,
+        std::unique_ptr<webrtc::SessionDescriptionInterface>
+            current_remote_description) {
   CHECK(main_task_runner_->BelongsToCurrentThread());
   WebRtcSetDescriptionObserver::States states;
   states.signaling_state = signaling_state;
@@ -116,6 +137,8 @@ void WebRtcSetDescriptionObserverHandlerImpl::
   states.transceiver_states = transceiver_state_surfacer.ObtainStates();
   states.pending_local_description = std::move(pending_local_description);
   states.current_local_description = std::move(current_local_description);
+  states.pending_remote_description = std::move(pending_remote_description);
+  states.current_remote_description = std::move(current_remote_description);
   observer_->OnSetDescriptionComplete(std::move(error), std::move(states));
 }
 

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

@@ -30,6 +30,14 @@
 
 namespace blink {
 
+// Copies the session description.
+// Note: At the time of writing, third_party/webrtc/pc/sdp_utils.h's
+// webrtc::CloneSessionDescription() creates a copy that does not include
+// candidates added with AddIceCandidate. This is why we need our own copy
+// function, which copies everything.
+std::unique_ptr<webrtc::SessionDescriptionInterface> CopySessionDescription(
+    const webrtc::SessionDescriptionInterface* description);
+
 // The blink layer correspondent of the setLocalDescription() observer
 // (webrtc::SetSessionDescriptionObserver) and setRemoteDescription() observer
 // (webrtc::SetRemoteDescriptionObserverInterface). The implementation should
@@ -51,15 +59,14 @@ class MODULES_EXPORT WebRtcSetDescriptionObserver
     webrtc::PeerConnectionInterface::SignalingState signaling_state;
     blink::WebRTCSctpTransportSnapshot sctp_transport_state;
     std::vector<blink::RtpTransceiverState> transceiver_states;
-    // For now, the session descriptions are only surfaced for the sake of
-    // showing up in chrome://webrtc-internals/ when implicit
-    // setLocalDescription() resolves.
-    // TODO(https://crbug.com/788558): Surface all states to blink at the same,
-    // time, including [current/pending][Local/Remote]Description.
     std::unique_ptr<webrtc::SessionDescriptionInterface>
         pending_local_description;
     std::unique_ptr<webrtc::SessionDescriptionInterface>
         current_local_description;
+    std::unique_ptr<webrtc::SessionDescriptionInterface>
+        pending_remote_description;
+    std::unique_ptr<webrtc::SessionDescriptionInterface>
+        current_remote_description;
 
     DISALLOW_COPY_AND_ASSIGN(States);
   };
@@ -117,7 +124,11 @@ class MODULES_EXPORT WebRtcSetDescriptionObserverHandlerImpl
       std::unique_ptr<webrtc::SessionDescriptionInterface>
           pending_local_description,
       std::unique_ptr<webrtc::SessionDescriptionInterface>
-          current_local_description);
+          current_local_description,
+      std::unique_ptr<webrtc::SessionDescriptionInterface>
+          pending_remote_description,
+      std::unique_ptr<webrtc::SessionDescriptionInterface>
+          current_remote_description);
 
   scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> signaling_task_runner_;

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

@@ -43,8 +43,9 @@
 namespace blink {
 
 class RTCIceCandidatePlatform;
-class RTCRtpTransceiverPlatform;
 class RTCRtpReceiverPlatform;
+class RTCRtpTransceiverPlatform;
+class RTCSessionDescriptionPlatform;
 
 struct PLATFORM_EXPORT WebRTCSctpTransportSnapshot {
   rtc::scoped_refptr<webrtc::SctpTransportInterface> transport;
@@ -66,6 +67,11 @@ class PLATFORM_EXPORT RTCPeerConnectionHandlerClient {
                                    const String& url,
                                    int error_code,
                                    const String& error_text) = 0;
+  virtual void DidChangeSessionDescriptions(
+      RTCSessionDescriptionPlatform* pending_local_description,
+      RTCSessionDescriptionPlatform* current_local_description,
+      RTCSessionDescriptionPlatform* pending_remote_description,
+      RTCSessionDescriptionPlatform* current_remote_description) = 0;
   virtual void DidChangeSignalingState(
       webrtc::PeerConnectionInterface::SignalingState) = 0;
   virtual void DidChangeIceGatheringState(

third_party/blink/web_tests/external/wpt/webrtc/RTCPeerConnection-description-attributes-timing.https.html

+<!doctype html>
+<meta charset=utf-8>
+<title></title>
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
+<script>
+'use strict';
+
+promise_test(async t => {
+  const pc = new RTCPeerConnection();
+  t.add_cleanup(() => pc.close());
+  const offer = await pc.createOffer();
+
+  assert_equals(pc.pendingLocalDescription, null,
+                'pendingLocalDescription is null before setLocalDescription');
+  const promise = pc.setLocalDescription(offer);
+  assert_equals(pc.pendingLocalDescription, null,
+                'pendingLocalDescription is still null while promise pending');
+  await promise;
+  assert_not_equals(pc.pendingLocalDescription, null,
+                    'pendingLocalDescription is not null after await');
+}, "pendingLocalDescription is surfaced at the right time");
+
+promise_test(async t => {
+  const pc = new RTCPeerConnection();
+  t.add_cleanup(() => pc.close());
+  const offer = await pc.createOffer();
+
+  assert_equals(pc.pendingRemoteDescription, null,
+                'pendingRemoteDescription is null before setRemoteDescription');
+  const promise = pc.setRemoteDescription(offer);
+  assert_equals(pc.pendingRemoteDescription, null,
+                'pendingRemoteDescription is still null while promise pending');
+  await promise;
+  assert_not_equals(pc.pendingRemoteDescription, null,
+                    'pendingRemoteDescription is not null after await');
+}, "pendingRemoteDescription is surfaced at the right time");
+
+promise_test(async t => {
+  const pc1 = new RTCPeerConnection();
+  t.add_cleanup(() => pc1.close());
+  const pc2 = new RTCPeerConnection();
+  t.add_cleanup(() => pc2.close());
+
+  const offer = await pc1.createOffer();
+  await pc1.setLocalDescription(offer);
+  await pc2.setRemoteDescription(offer);
+  const answer = await pc2.createAnswer();
+
+  assert_equals(pc2.currentLocalDescription, null,
+                'currentLocalDescription is null before setLocalDescription');
+  const promise = pc2.setLocalDescription(answer);
+  assert_equals(pc2.currentLocalDescription, null,
+                'currentLocalDescription is still null while promise pending');
+  await promise;
+  assert_not_equals(pc2.currentLocalDescription, null,
+                    'currentLocalDescription is not null after await');
+}, "currentLocalDescription is surfaced at the right time");
+
+promise_test(async t => {
+  const pc1 = new RTCPeerConnection();
+  t.add_cleanup(() => pc1.close());
+  const pc2 = new RTCPeerConnection();
+  t.add_cleanup(() => pc2.close());
+
+  const offer = await pc1.createOffer();
+  await pc1.setLocalDescription(offer);
+  await pc2.setRemoteDescription(offer);
+  const answer = await pc2.createAnswer();
+
+  assert_equals(pc1.currentRemoteDescription, null,
+                'currentRemoteDescription is null before setRemoteDescription');
+  const promise = pc1.setRemoteDescription(answer);
+  assert_equals(pc1.currentRemoteDescription, null,
+                'currentRemoteDescription is still null while promise pending');
+  await promise;
+  assert_not_equals(pc1.currentRemoteDescription, null,
+                    'currentRemoteDescription is not null after await');
+}, "currentRemoteDescription is surfaced at the right time");
+
+</script>

third_party/blink/web_tests/external/wpt/webrtc/RTCPeerConnection-setLocalDescription-answer-expected.txt

@@ -5,6 +5,6 @@ PASS setLocalDescription() with answer not created by own createAnswer() should
 FAIL Calling setLocalDescription(answer) from stable state should reject with InvalidModificationError promise_rejects_dom: function "function() { throw e }" threw object "OperationError: Failed to execute 'setLocalDescription' on 'RTCPeerConnection': Failed to set local answer sdp: Called in wrong state: stable" that is not a DOMException InvalidModificationError: property "code" is equal to 0, expected 13
 FAIL Calling setLocalDescription(answer) from have-local-offer state should reject with InvalidModificationError promise_rejects_dom: function "function() { throw e }" threw object "OperationError: Failed to execute 'setLocalDescription' on 'RTCPeerConnection': Failed to set local answer sdp: Called in wrong state: have-local-offer" that is not a DOMException InvalidModificationError: property "code" is equal to 0, expected 13
 PASS Setting previously generated answer after a call to createOffer should work
-FAIL setLocalDescription(answer) should update internal state with a queued task, in the right order assert_not_equals: pendingRemoteDescription should not be set synchronously after a call to sLD got disallowed value null
+PASS setLocalDescription(answer) should update internal state with a queued task, in the right order
 Harness: the test ran to completion.
 

third_party/blink/web_tests/external/wpt/webrtc/RTCPeerConnection-setLocalDescription-offer-expected.txt

@@ -6,6 +6,6 @@ FAIL Set created offer other than last offer should reject with InvalidModificat
 PASS Creating and setting offer multiple times should succeed
 PASS Setting previously generated offer after a call to createAnswer should work
 PASS Negotiation works when there has been a repeated setLocalDescription(offer)
-FAIL setLocalDescription(offer) should update internal state with a queued task, in the right order assert_equals: pendingRemoteDescription should never be set due to sLD expected null but got object "[object RTCSessionDescription]"
+PASS setLocalDescription(offer) should update internal state with a queued task, in the right order
 Harness: the test ran to completion.
 

third_party/blink/web_tests/external/wpt/webrtc/RTCPeerConnection-setLocalDescription-rollback-expected.txt

-This is a testharness.js-based test.
-PASS setLocalDescription(rollback) from have-local-offer state should reset back to stable state
-PASS setLocalDescription(rollback) from stable state should reject with InvalidStateError
-PASS setLocalDescription(rollback) after setting answer description should reject with InvalidStateError
-PASS setLocalDescription(rollback) should ignore invalid sdp content and succeed
-FAIL setLocalDescription(rollback) should update internal state with a queued tassk, in the right order assert_not_equals: pendingLocalDescription should not be set synchronously after a call to sLD got disallowed value null
-Harness: the test ran to completion.
-

third_party/blink/web_tests/virtual/webrtc-wpt-plan-b/external/wpt/webrtc/RTCPeerConnection-setLocalDescription-answer-expected.txt

@@ -5,6 +5,6 @@ PASS setLocalDescription() with answer not created by own createAnswer() should
 FAIL Calling setLocalDescription(answer) from stable state should reject with InvalidModificationError promise_rejects_dom: function "function() { throw e }" threw object "OperationError: Failed to execute 'setLocalDescription' on 'RTCPeerConnection': Failed to set local answer sdp: Called in wrong state: stable" that is not a DOMException InvalidModificationError: property "code" is equal to 0, expected 13
 FAIL Calling setLocalDescription(answer) from have-local-offer state should reject with InvalidModificationError promise_rejects_dom: function "function() { throw e }" threw object "OperationError: Failed to execute 'setLocalDescription' on 'RTCPeerConnection': Failed to set local answer sdp: Called in wrong state: have-local-offer" that is not a DOMException InvalidModificationError: property "code" is equal to 0, expected 13
 FAIL Setting previously generated answer after a call to createOffer should work promise_test: Unhandled rejection with value: object "OperationError: Failed to execute 'setRemoteDescription' on 'RTCPeerConnection': Rollback not supported in Plan B"
-FAIL setLocalDescription(answer) should update internal state with a queued task, in the right order assert_not_equals: pendingRemoteDescription should not be set synchronously after a call to sLD got disallowed value null
+PASS setLocalDescription(answer) should update internal state with a queued task, in the right order
 Harness: the test ran to completion.
 

third_party/blink/web_tests/virtual/webrtc-wpt-plan-b/external/wpt/webrtc/RTCPeerConnection-setLocalDescription-offer-expected.txt

@@ -6,6 +6,6 @@ FAIL Set created offer other than last offer should reject with InvalidModificat
 PASS Creating and setting offer multiple times should succeed
 FAIL Setting previously generated offer after a call to createAnswer should work promise_test: Unhandled rejection with value: object "OperationError: Failed to execute 'setRemoteDescription' on 'RTCPeerConnection': Rollback not supported in Plan B"
 FAIL Negotiation works when there has been a repeated setLocalDescription(offer) assert_equals: expected 1 but got 0
-FAIL setLocalDescription(offer) should update internal state with a queued task, in the right order assert_equals: pendingRemoteDescription should never be set due to sLD expected null but got object "[object RTCSessionDescription]"
+PASS setLocalDescription(offer) should update internal state with a queued task, in the right order
 Harness: the test ran to completion.