diff --git a/talk/app/webrtc/datachannel.cc b/talk/app/webrtc/datachannel.cc
index 3a6046e81..6f3048718 100644
--- a/talk/app/webrtc/datachannel.cc
+++ b/talk/app/webrtc/datachannel.cc
@@ -38,6 +38,10 @@ namespace webrtc {
 static size_t kMaxQueuedReceivedDataPackets = 100;
 static size_t kMaxQueuedSendDataPackets = 100;
 
+enum {
+  MSG_CHANNELREADY,
+};
+
 talk_base::scoped_refptr<DataChannel> DataChannel::Create(
     DataChannelProviderInterface* provider,
     cricket::DataChannelType dct,
@@ -95,6 +99,15 @@ bool DataChannel::Init(const DataChannelInit* config) {
     // Try to connect to the transport in case the transport channel already
     // exists.
     OnTransportChannelCreated();
+
+    // Checks if the transport is ready to send because the initial channel
+    // ready signal may have been sent before the DataChannel creation.
+    // This has to be done async because the upper layer objects (e.g.
+    // Chrome glue and WebKit) are not wired up properly until after this
+    // function returns.
+    if (provider_->ReadyToSendData()) {
+      talk_base::Thread::Current()->Post(this, MSG_CHANNELREADY, NULL);
+    }
   }
 
   return true;
@@ -217,6 +230,14 @@ void DataChannel::SetSendSsrc(uint32 send_ssrc) {
   UpdateState();
 }
 
+void DataChannel::OnMessage(talk_base::Message* msg) {
+  switch (msg->message_id) {
+    case MSG_CHANNELREADY:
+      OnChannelReady(true);
+      break;
+  }
+}
+
 // The underlaying data engine is closing.
 // This function makes sure the DataChannel is disconnected and changes state to
 // kClosed.
diff --git a/talk/app/webrtc/datachannel.h b/talk/app/webrtc/datachannel.h
index 0d67293db..5635e63e6 100644
--- a/talk/app/webrtc/datachannel.h
+++ b/talk/app/webrtc/datachannel.h
@@ -33,6 +33,7 @@
 
 #include "talk/app/webrtc/datachannelinterface.h"
 #include "talk/app/webrtc/proxy.h"
+#include "talk/base/messagehandler.h"
 #include "talk/base/scoped_ref_ptr.h"
 #include "talk/base/sigslot.h"
 #include "talk/media/base/mediachannel.h"
@@ -60,6 +61,8 @@ class DataChannelProviderInterface {
   virtual void RemoveRtpDataStream(uint32 send_ssrc, uint32 recv_ssrc) = 0;
   // Removes the data channel SID from the transport for SCTP.
   virtual void RemoveSctpDataStream(uint32 sid) = 0;
+  // Returns true if the transport channel is ready to send data.
+  virtual bool ReadyToSendData() const = 0;
 
  protected:
   virtual ~DataChannelProviderInterface() {}
@@ -81,7 +84,8 @@ class DataChannelProviderInterface {
 // kClosed: Both UpdateReceiveSsrc and UpdateSendSsrc has been called with
 //          SSRC==0.
 class DataChannel : public DataChannelInterface,
-                    public sigslot::has_slots<> {
+                    public sigslot::has_slots<>,
+                    public talk_base::MessageHandler {
  public:
   static talk_base::scoped_refptr<DataChannel> Create(
       DataChannelProviderInterface* provider,
@@ -109,6 +113,9 @@ class DataChannel : public DataChannelInterface,
   virtual DataState state() const { return state_; }
   virtual bool Send(const DataBuffer& buffer);
 
+  // talk_base::MessageHandler override.
+  virtual void OnMessage(talk_base::Message* msg);
+
   // Called if the underlying data engine is closing.
   void OnDataEngineClose();
 
diff --git a/talk/app/webrtc/datachannel_unittest.cc b/talk/app/webrtc/datachannel_unittest.cc
index 5d298110c..dba24a2db 100644
--- a/talk/app/webrtc/datachannel_unittest.cc
+++ b/talk/app/webrtc/datachannel_unittest.cc
@@ -39,11 +39,12 @@ class SctpDataChannelTest : public testing::Test {
   }
 
   void SetChannelReady() {
+    provider_.set_transport_available(true);
     webrtc_data_channel_->OnTransportChannelCreated();
     if (webrtc_data_channel_->id() < 0) {
       webrtc_data_channel_->SetSctpSid(0);
     }
-    webrtc_data_channel_->OnChannelReady(true);
+    provider_.set_ready_to_send(true);
   }
 
   webrtc::DataChannelInit init_;
@@ -53,27 +54,28 @@ class SctpDataChannelTest : public testing::Test {
 
 // Verifies that the data channel is connected to the transport after creation.
 TEST_F(SctpDataChannelTest, ConnectedToTransportOnCreated) {
-  EXPECT_TRUE(provider_.IsConnected(webrtc_data_channel_.get()));
-  // The sid is not set yet, so it should not have added the streams.
-  EXPECT_FALSE(provider_.IsSendStreamAdded(webrtc_data_channel_->id()));
-  EXPECT_FALSE(provider_.IsRecvStreamAdded(webrtc_data_channel_->id()));
+  provider_.set_transport_available(true);
+  talk_base::scoped_refptr<DataChannel> dc = DataChannel::Create(
+      &provider_, cricket::DCT_SCTP, "test1", &init_);
 
-  webrtc_data_channel_->SetSctpSid(0);
-  EXPECT_TRUE(provider_.IsSendStreamAdded(webrtc_data_channel_->id()));
-  EXPECT_TRUE(provider_.IsRecvStreamAdded(webrtc_data_channel_->id()));
+  EXPECT_TRUE(provider_.IsConnected(dc.get()));
+  // The sid is not set yet, so it should not have added the streams.
+  EXPECT_FALSE(provider_.IsSendStreamAdded(dc->id()));
+  EXPECT_FALSE(provider_.IsRecvStreamAdded(dc->id()));
+
+  dc->SetSctpSid(0);
+  EXPECT_TRUE(provider_.IsSendStreamAdded(dc->id()));
+  EXPECT_TRUE(provider_.IsRecvStreamAdded(dc->id()));
 }
 
 // Verifies that the data channel is connected to the transport if the transport
 // is not available initially and becomes available later.
 TEST_F(SctpDataChannelTest, ConnectedAfterTransportBecomesAvailable) {
-  provider_.set_transport_available(false);
-  talk_base::scoped_refptr<DataChannel> dc = DataChannel::Create(
-      &provider_, cricket::DCT_SCTP, "test1", &init_);
-  EXPECT_FALSE(provider_.IsConnected(dc.get()));
+  EXPECT_FALSE(provider_.IsConnected(webrtc_data_channel_.get()));
 
   provider_.set_transport_available(true);
-  dc->OnTransportChannelCreated();
-  EXPECT_TRUE(provider_.IsConnected(dc.get()));
+  webrtc_data_channel_->OnTransportChannelCreated();
+  EXPECT_TRUE(provider_.IsConnected(webrtc_data_channel_.get()));
 }
 
 // Tests the state of the data channel.
@@ -81,6 +83,7 @@ TEST_F(SctpDataChannelTest, StateTransition) {
   EXPECT_EQ(webrtc::DataChannelInterface::kConnecting,
             webrtc_data_channel_->state());
   SetChannelReady();
+
   EXPECT_EQ(webrtc::DataChannelInterface::kOpen, webrtc_data_channel_->state());
   webrtc_data_channel_->Close();
   EXPECT_EQ(webrtc::DataChannelInterface::kClosed,
@@ -132,3 +135,16 @@ TEST_F(SctpDataChannelTest, OpenMessageSent) {
   EXPECT_EQ(provider_.last_send_data_params().ssrc,
             static_cast<uint32>(webrtc_data_channel_->id()));
 }
+
+// Tests that the DataChannel created after transport gets ready can enter OPEN
+// state.
+TEST_F(SctpDataChannelTest, LateCreatedChannelTransitionToOpen) {
+  SetChannelReady();
+  webrtc::DataChannelInit init;
+  init.id = 1;
+  talk_base::scoped_refptr<DataChannel> dc =
+      DataChannel::Create(&provider_, cricket::DCT_SCTP, "test1", &init);
+  EXPECT_EQ(webrtc::DataChannelInterface::kConnecting, dc->state());
+  EXPECT_TRUE_WAIT(webrtc::DataChannelInterface::kOpen == dc->state(),
+                   1000);
+}
diff --git a/talk/app/webrtc/mediastreamsignaling.cc b/talk/app/webrtc/mediastreamsignaling.cc
index 91dde24e0..8d2542569 100644
--- a/talk/app/webrtc/mediastreamsignaling.cc
+++ b/talk/app/webrtc/mediastreamsignaling.cc
@@ -276,8 +276,6 @@ bool MediaStreamSignaling::AddDataChannelFromOpenMessage(
   }
   data_channels_[label] = channel;
   stream_observer_->OnAddDataChannel(channel);
-  // It's immediately ready to use.
-  channel->OnChannelReady(true);
   return true;
 }
 
diff --git a/talk/app/webrtc/test/fakedatachannelprovider.h b/talk/app/webrtc/test/fakedatachannelprovider.h
index 332641930..429f4dff1 100644
--- a/talk/app/webrtc/test/fakedatachannelprovider.h
+++ b/talk/app/webrtc/test/fakedatachannelprovider.h
@@ -30,14 +30,15 @@
 class FakeDataChannelProvider : public webrtc::DataChannelProviderInterface {
  public:
   FakeDataChannelProvider()
-      : id_allocation_should_fail_(false),
-        send_blocked_(false),
-        transport_available_(true) {}
+      : send_blocked_(false),
+        transport_available_(false),
+        ready_to_send_(false) {}
   virtual ~FakeDataChannelProvider() {}
 
   virtual bool SendData(const cricket::SendDataParams& params,
                         const talk_base::Buffer& payload,
                         cricket::SendDataResult* result) OVERRIDE {
+    ASSERT(ready_to_send_ && transport_available_);
     if (send_blocked_) {
       *result = cricket::SDR_BLOCK;
       return false;
@@ -45,6 +46,7 @@ class FakeDataChannelProvider : public webrtc::DataChannelProviderInterface {
     last_send_data_params_ = params;
     return true;
   }
+
   virtual bool ConnectDataChannel(webrtc::DataChannel* data_channel) OVERRIDE {
     ASSERT(connected_channels_.find(data_channel) == connected_channels_.end());
     if (!transport_available_) {
@@ -54,55 +56,98 @@ class FakeDataChannelProvider : public webrtc::DataChannelProviderInterface {
     connected_channels_.insert(data_channel);
     return true;
   }
+
   virtual void DisconnectDataChannel(
       webrtc::DataChannel* data_channel) OVERRIDE {
     ASSERT(connected_channels_.find(data_channel) != connected_channels_.end());
     LOG(LS_INFO) << "DataChannel disconnected " << data_channel;
     connected_channels_.erase(data_channel);
   }
+
   virtual void AddRtpDataStream(uint32 send_ssrc, uint32 recv_ssrc) OVERRIDE {
+    if (!transport_available_) {
+      return;
+    }
     send_ssrcs_.insert(send_ssrc);
     recv_ssrcs_.insert(recv_ssrc);
   }
+
   virtual void AddSctpDataStream(uint32 sid) OVERRIDE {
+    if (!transport_available_) {
+      return;
+    }
     AddRtpDataStream(sid, sid);
   }
+
   virtual void RemoveRtpDataStream(
       uint32 send_ssrc, uint32 recv_ssrc) OVERRIDE {
     send_ssrcs_.erase(send_ssrc);
     recv_ssrcs_.erase(recv_ssrc);
   }
+
   virtual void RemoveSctpDataStream(uint32 sid) OVERRIDE {
     RemoveRtpDataStream(sid, sid);
   }
 
+  virtual bool ReadyToSendData() const OVERRIDE {
+    return ready_to_send_;
+  }
+
+  // Set true to emulate the SCTP stream being blocked by congestion control.
   void set_send_blocked(bool blocked) {
     send_blocked_ = blocked;
+    if (!blocked) {
+      std::set<webrtc::DataChannel*>::iterator it;
+      for (it = connected_channels_.begin();
+           it != connected_channels_.end();
+           ++it) {
+        (*it)->OnChannelReady(true);
+      }
+    }
   }
-  cricket::SendDataParams last_send_data_params() const {
-    return last_send_data_params_;
-  }
-  void set_id_allocaiton_should_fail(bool fail) {
-    id_allocation_should_fail_ = fail;
-  }
+
+  // Set true to emulate the transport channel creation, e.g. after
+  // setLocalDescription/setRemoteDescription called with data content.
   void set_transport_available(bool available) {
     transport_available_ = available;
   }
+
+  // Set true to emulate the transport ReadyToSendData signal when the transport
+  // becomes writable for the first time.
+  void set_ready_to_send(bool ready) {
+    ASSERT(transport_available_);
+    ready_to_send_ = ready;
+    if (ready) {
+      std::set<webrtc::DataChannel*>::iterator it;
+      for (it = connected_channels_.begin();
+           it != connected_channels_.end();
+           ++it) {
+        (*it)->OnChannelReady(true);
+      }
+    }
+  }
+
+  cricket::SendDataParams last_send_data_params() const {
+    return last_send_data_params_;
+  }
+
   bool IsConnected(webrtc::DataChannel* data_channel) const {
     return connected_channels_.find(data_channel) != connected_channels_.end();
   }
+
   bool IsSendStreamAdded(uint32 stream) const {
     return send_ssrcs_.find(stream) != send_ssrcs_.end();
   }
+
   bool IsRecvStreamAdded(uint32 stream) const {
     return recv_ssrcs_.find(stream) != recv_ssrcs_.end();
   }
 
  private:
   cricket::SendDataParams last_send_data_params_;
-  bool id_allocation_should_fail_;
   bool send_blocked_;
   bool transport_available_;
+  bool ready_to_send_;
   std::set<webrtc::DataChannel*> connected_channels_;
   std::set<uint32> send_ssrcs_;
   std::set<uint32> recv_ssrcs_;
diff --git a/talk/app/webrtc/webrtcsession.cc b/talk/app/webrtc/webrtcsession.cc
index a96c2da8c..5935ea046 100644
--- a/talk/app/webrtc/webrtcsession.cc
+++ b/talk/app/webrtc/webrtcsession.cc
@@ -1024,6 +1024,10 @@ void WebRtcSession::RemoveSctpDataStream(uint32 sid) {
   RemoveRtpDataStream(sid, sid);
 }
 
+bool WebRtcSession::ReadyToSendData() const {
+  return data_channel_.get() && data_channel_->ready_to_send_data();
+}
+
 talk_base::scoped_refptr<DataChannel> WebRtcSession::CreateDataChannel(
     const std::string& label,
     const DataChannelInit* config) {
diff --git a/talk/app/webrtc/webrtcsession.h b/talk/app/webrtc/webrtcsession.h
index 893ab3fb4..4a39a11d1 100644
--- a/talk/app/webrtc/webrtcsession.h
+++ b/talk/app/webrtc/webrtcsession.h
@@ -194,6 +194,7 @@ class WebRtcSession : public cricket::BaseSession,
   virtual void AddSctpDataStream(uint32 sid) OVERRIDE;
   virtual void RemoveRtpDataStream(uint32 send_ssrc, uint32 recv_ssrc) OVERRIDE;
   virtual void RemoveSctpDataStream(uint32 sid) OVERRIDE;
+  virtual bool ReadyToSendData() const OVERRIDE;
 
   talk_base::scoped_refptr<DataChannel> CreateDataChannel(
       const std::string& label,
diff --git a/talk/base/common.h b/talk/base/common.h
index 6350baf1e..d557639e2 100644
--- a/talk/base/common.h
+++ b/talk/base/common.h
@@ -198,7 +198,7 @@ inline bool ImplicitCastToBool(bool result) { return result; }
 // TODO(ajm): Hack to avoid multiple definitions until the base/ of webrtc and
 // libjingle are merged.
 #if !defined(WARN_UNUSED_RESULT)
-#if defined(COMPILER_GCC)
+#if defined(__GNUC__)
 #define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
 #else
 #define WARN_UNUSED_RESULT
diff --git a/talk/session/media/channel.cc b/talk/session/media/channel.cc
index 1a3063d44..e0aff8999 100644
--- a/talk/session/media/channel.cc
+++ b/talk/session/media/channel.cc
@@ -2477,7 +2477,8 @@ DataChannel::DataChannel(talk_base::Thread* thread,
                          bool rtcp)
     // MediaEngine is NULL
     : BaseChannel(thread, NULL, media_channel, session, content_name, rtcp),
-      data_channel_type_(cricket::DCT_NONE) {
+      data_channel_type_(cricket::DCT_NONE),
+      ready_to_send_data_(false) {
 }
 
 DataChannel::~DataChannel() {
@@ -2701,7 +2702,8 @@ void DataChannel::OnMessage(talk_base::Message *pmsg) {
     case MSG_READYTOSENDDATA: {
       DataChannelReadyToSendMessageData* data =
           static_cast<DataChannelReadyToSendMessageData*>(pmsg->pdata);
-      SignalReadyToSendData(data->data());
+      ready_to_send_data_ = data->data();
+      SignalReadyToSendData(ready_to_send_data_);
       delete data;
       break;
     }
diff --git a/talk/session/media/channel.h b/talk/session/media/channel.h
index 51fb575dd..27a81a6d5 100644
--- a/talk/session/media/channel.h
+++ b/talk/session/media/channel.h
@@ -610,6 +610,11 @@ class DataChannel : public BaseChannel {
   void StartMediaMonitor(int cms);
   void StopMediaMonitor();
 
+  // Should be called on the signaling thread only.
+  bool ready_to_send_data() const {
+    return ready_to_send_data_;
+  }
+
   sigslot::signal2<DataChannel*, const DataMediaInfo&> SignalMediaMonitor;
   sigslot::signal2<DataChannel*, const std::vector<ConnectionInfo>&>
       SignalConnectionMonitor;
@@ -714,6 +719,7 @@ class DataChannel : public BaseChannel {
   // TODO(pthatcher): Make a separate SctpDataChannel and
   // RtpDataChannel instead of using this.
   DataChannelType data_channel_type_;
+  bool ready_to_send_data_;
 };
 
 }  // namespace cricket