Reland of Moving MediaStreamSignaling logic into PeerConnection.

talk/app/webrtc/datachannel.h

Index: talk/app/webrtc/datachannel.h
diff --git a/talk/app/webrtc/datachannel.h b/talk/app/webrtc/datachannel.h
index 4506f71b146c71f95ab22a04fbcffca97b43bb32..2713ae3b553ed7a79f32de9f34a214c3396e1877 100644
--- a/talk/app/webrtc/datachannel.h
+++ b/talk/app/webrtc/datachannel.h
@@ -29,6 +29,7 @@
 #define TALK_APP_WEBRTC_DATACHANNEL_H_
 
 #include <deque>
+#include <set>
 #include <string>
 
 #include "talk/app/webrtc/datachannelinterface.h"
@@ -83,6 +84,28 @@ struct InternalDataChannelInit : public DataChannelInit {
   OpenHandshakeRole open_handshake_role;
 };
 
+// Helper class to allocate unique IDs for SCTP DataChannels
+class SctpSidAllocator {
+ public:
+  // Gets the first unused odd/even id based on the DTLS role. If |role| is
+  // SSL_CLIENT, the allocated id starts from 0 and takes even numbers;
+  // otherwise, the id starts from 1 and takes odd numbers.
+  // Returns false if no id can be allocated.
+  bool AllocateSid(rtc::SSLRole role, int* sid);
+
+  // Attempts to reserve a specific sid. Returns false if it's unavailable.
+  bool ReserveSid(int sid);
+
+  // Indicates that |sid| isn't in use any more, and is thus available again.
+  void ReleaseSid(int sid);
+
+ private:
+  // Checks if |sid| is available to be assigned to a new SCTP data channel.
+  bool IsSidAvailable(int sid) const;
+
+  std::set<int> used_sids_;
+};
+
 // DataChannel is a an implementation of the DataChannelInterface based on
 // libjingle's data engine. It provides an implementation of unreliable or
 // reliabledata channels. Currently this class is specifically designed to use
@@ -129,9 +152,6 @@ class DataChannel : public DataChannelInterface,
   // rtc::MessageHandler override.
   virtual void OnMessage(rtc::Message* msg);
 
-  // Called if the underlying data engine is closing.
-  void OnDataEngineClose();
-
   // Called when the channel's ready to use.  That can happen when the
   // underlying DataMediaChannel becomes ready, or when this channel is a new
   // stream on an existing DataMediaChannel, and we've finished negotiation.
@@ -141,6 +161,7 @@ class DataChannel : public DataChannelInterface,
   void OnDataReceived(cricket::DataChannel* channel,
                       const cricket::ReceiveDataParams& params,
                       const rtc::Buffer& payload);
+  void OnStreamClosedRemotely(uint32_t sid);
 
   // The remote peer request that this channel should be closed.
   void RemotePeerRequestClose();
@@ -151,7 +172,10 @@ class DataChannel : public DataChannelInterface,
   // be called once.
   void SetSctpSid(int sid);
   // Called when the transport channel is created.
+  // Only needs to be called for SCTP data channels.
   void OnTransportChannelCreated();
+  // Called when the transport channel is destroyed.
+  void OnTransportChannelDestroyed();
 
   // The following methods are for RTP only.
 
@@ -167,6 +191,11 @@ class DataChannel : public DataChannelInterface,
     return data_channel_type_;
   }
 
+  // Emitted when state transitions to kClosed.
+  // In the case of SCTP channels, this signal can be used to tell when the
+  // channel's sid is free.
+  sigslot::signal1<DataChannel*> SignalClosed;
+
  protected:
   DataChannel(DataChannelProviderInterface* client,
               cricket::DataChannelType dct,
@@ -247,16 +276,6 @@ class DataChannel : public DataChannelInterface,
   PacketQueue queued_send_data_;
 };
 
-class DataChannelFactory {
- public:
-  virtual rtc::scoped_refptr<DataChannel> CreateDataChannel(
-      const std::string& label,
-      const InternalDataChannelInit* config) = 0;
-
- protected:
-  virtual ~DataChannelFactory() {}
-};
-
 // Define proxy for DataChannelInterface.
 BEGIN_PROXY_MAP(DataChannel)
   PROXY_METHOD1(void, RegisterObserver, DataChannelObserver*)