RemoteMediaStreamImpl using WebRtcMediaStreamTrackMap.

content/renderer/media/webrtc/webrtc_media_stream_track_adapter_map.cc

 // Copyright (c) 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/media/webrtc/webrtc_media_stream_track_adapter_map.h"
 
 #include <utility>
 
 #include "content/renderer/media/webrtc/peer_connection_dependency_factory.h"
 
@@ skipping 29 matching lines @@
   if (entry()->adapter->HasOneRef()) {
     entry()->adapter->Dispose();
     if (type_ == Type::kLocal)
       map_->local_track_adapters_.erase(it_);
     else
       map_->remote_track_adapters_.erase(it_);
   }
 }
 
 WebRtcMediaStreamTrackAdapterMap::WebRtcMediaStreamTrackAdapterMap(
-    PeerConnectionDependencyFactory* const factory,
-    const scoped_refptr<base::SingleThreadTaskRunner>& main_thread)
-    : factory_(factory), main_thread_(main_thread) {
+    PeerConnectionDependencyFactory* const factory)
+    : factory_(factory), main_thread_(base::ThreadTaskRunnerHandle::Get()) {

[Guido Urdaneta, 2017/06/12 14:25:29]

How do you know this is the main thread?
Shouldn't the variable have another name?

[hbos_chromium, 2017/06/12 15:05:21]

It has to be the main thread since it is used by WebRtcMediaStreamTrackAdapter
which require it to be the main thread. (Which thread its components is
initialized depends on this threading model of main and signaling thread.)

Would you prefer if I pass main_thread in as an argument like before, forcing
the caller to ensure that it is the main thread?

(Code not updated because I have to leave for the day)

[Guido Urdaneta, 2017/06/12 15:18:35]

It's fine this way then. Just add a comment saying that this is intended to be
constructed on the main thread.

   DCHECK(factory_);
   DCHECK(main_thread_);
 }
 
 WebRtcMediaStreamTrackAdapterMap::~WebRtcMediaStreamTrackAdapterMap() {
   DCHECK(local_track_adapters_.empty());
   DCHECK(remote_track_adapters_.empty());
 }
 
 std::unique_ptr<WebRtcMediaStreamTrackAdapterMap::AdapterRef>
@@ skipping 20 matching lines @@
 
 std::unique_ptr<WebRtcMediaStreamTrackAdapterMap::AdapterRef>
 WebRtcMediaStreamTrackAdapterMap::GetRemoteTrackAdapter(const std::string& id) {
   return GetTrackAdapter(AdapterRef::Type::kRemote, id);
 }
 
 std::unique_ptr<WebRtcMediaStreamTrackAdapterMap::AdapterRef>
 WebRtcMediaStreamTrackAdapterMap::GetOrCreateRemoteTrackAdapter(
     webrtc::MediaStreamTrackInterface* webrtc_track) {
   DCHECK(webrtc_track);
-  DCHECK(factory_->GetWebRtcSignalingThread()->BelongsToCurrentThread());
+  DCHECK(!main_thread_->BelongsToCurrentThread());
   return GetOrCreateTrackAdapter(

[Guido Urdaneta, 2017/06/12 14:25:29]

What happens if there are concurrent calls to this from different threads?

[hbos_chromium, 2017/06/12 15:05:21]

This is thread safe thanks to use of lock_.

[hbos_chromium, 2017/06/12 15:07:51]

But the WebRtcMediaStreamTrackAdapter needs this to be on the signaling thread
and doesn't allow other threads to invoke it by design.

[Guido Urdaneta, 2017/06/12 15:18:35]

Acknowledged.

       AdapterRef::Type::kRemote,
       base::Bind(&WebRtcMediaStreamTrackAdapter::CreateRemoteTrackAdapter,
                  factory_, main_thread_, webrtc_track),
       webrtc_track->id());
 }
 
 size_t WebRtcMediaStreamTrackAdapterMap::GetRemoteTrackCount() const {
   base::AutoLock scoped_lock(lock_);
   return remote_track_adapters_.size();
 }
@@ skipping 26 matching lines @@
   if (it == track_adapters->end()) {
     scoped_refptr<WebRtcMediaStreamTrackAdapter> adapter =
         create_adapter_callback.Run();
     it =
         track_adapters->insert(std::make_pair(id, AdapterEntry(adapter))).first;
   }
   return base::WrapUnique(new AdapterRef(this, type, it));
 }
 
 }  // namespace content