Relanding: Implement RTCConfiguration.iceCandidatePoolSize.

webrtc/api/peerconnection.cc

Index: webrtc/api/peerconnection.cc
diff --git a/webrtc/api/peerconnection.cc b/webrtc/api/peerconnection.cc
index 7f1f4523781685f062bfa0f7e8b639fd1cc1b8d4..21b37859105de73c0538f8e8c275e8d65481fa3f 100644
--- a/webrtc/api/peerconnection.cc
+++ b/webrtc/api/peerconnection.cc
@@ -522,6 +522,14 @@ PeerConnection::~PeerConnection() {
   for (const auto& receiver : receivers_) {
     receiver->Stop();
   }
+  // Destroy stats_ because it depends on session_.
+  stats_.reset(nullptr);
+  // Now destroy session_ before destroying other members,
+  // because its destruction fires signals (such as VoiceChannelDestroyed)
+  // which will trigger some final actions in PeerConnection...
+  session_.reset(nullptr);
+  // port_allocator_ lives on the worker thread and should be destroyed there.
+  worker_thread()->Invoke<void>([this] { port_allocator_.reset(nullptr); });
 }
 
 bool PeerConnection::Initialize(
@@ -543,7 +551,9 @@ bool PeerConnection::Initialize(
   if (!ParseIceServers(configuration.servers, &stun_servers, &turn_servers)) {
     return false;
   }
-  port_allocator_->SetIceServers(stun_servers, turn_servers);
+  worker_thread()->Invoke<void>(rtc::Bind(
+      &cricket::PortAllocator::SetConfiguration, port_allocator_.get(),

[pthatcher1, 2016/05/05 21:51:24]

I'm a little confused.  Some things on PortAllocator are accessed on the worker
thread (SetConfiguration) and others on the signaling thread (flags, set_flags,
set_step_delay).  It would be really nice to have the port_allocator_ only
accessed on one thread, even if that means the port allocator does its own
thread hopping, or making all calls here do thread hopping. 

[Taylor Brandstetter, 2016/05/06 03:53:34]

That's the way it's always been. I agree it should be fixed, I just thought it
may be better done in a separate CL. It seems... *relatively* simple though so
I'll do it in this one (I can revert if you think it's too complex).

This makes me realize we need more PeerConnection tests. For example, making
sure the PeerConnection calls PortAllocator::SetConfiguration AFTER applying the
other settings to the port allocator. Don't l-g-t-m the CL until I've done that.

+      stun_servers, turn_servers, configuration.ice_candidate_pool_size));
 
   // To handle both internal and externally created port allocator, we will
   // enable BUNDLE here.
@@ -1144,18 +1154,20 @@ void PeerConnection::SetRemoteDescription(
   signaling_thread()->Post(this, MSG_SET_SESSIONDESCRIPTION_SUCCESS, msg);
 }
 
-bool PeerConnection::SetConfiguration(const RTCConfiguration& config) {
+bool PeerConnection::SetConfiguration(const RTCConfiguration& configuration) {
   TRACE_EVENT0("webrtc", "PeerConnection::SetConfiguration");
   if (port_allocator_) {
     cricket::ServerAddresses stun_servers;
     std::vector<cricket::RelayServerConfig> turn_servers;
-    if (!ParseIceServers(config.servers, &stun_servers, &turn_servers)) {
+    if (!ParseIceServers(configuration.servers, &stun_servers, &turn_servers)) {
       return false;
     }
-    port_allocator_->SetIceServers(stun_servers, turn_servers);
+    worker_thread()->Invoke<void>(rtc::Bind(
+        &cricket::PortAllocator::SetConfiguration, port_allocator_.get(),
+        stun_servers, turn_servers, configuration.ice_candidate_pool_size));
   }
-  session_->SetIceConfig(session_->ParseIceConfig(config));
-  return session_->SetIceTransports(config.type);
+  session_->SetIceConfig(session_->ParseIceConfig(configuration));
+  return session_->SetIceTransports(configuration.type);
 }
 
 bool PeerConnection::AddIceCandidate(