Fixing issue with DTLS channel when using "presume writable" flag.

webrtc/p2p/base/dtlstransportchannel.cc

 /*
  *  Copyright 2011 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 229 matching lines @@
 
   bool reconnect = (dtls_ != nullptr);
 
   if (!SetupDtls()) {
     set_dtls_state(DTLS_TRANSPORT_FAILED);
     return false;
   }
 
   if (reconnect) {
     Reconnect();
+  } else {
+    // If the underlying channel is already writable by the time we receive
+    // a remote fingerprint, we may be able to start DTLS right away.
+    MaybeStartDtls();

[skvlad, 2016/07/12 21:53:52]

The other two calls wrap this in VERIFY() - do you think this should also be
done here?

[pthatcher1, 2016/07/13 00:04:19]

If the other call is inlined, then there would just be one call to
MaybeStartDtls here, outside of the if statement.

[Taylor Brandstetter, 2016/07/13 16:17:41]

If we always want to DCHECK that this succeeds, I'll just move the DCHECK into
the function itself and have it return void.

   }
 
   return true;
 }
 
 std::unique_ptr<rtc::SSLCertificate>
 DtlsTransportChannelWrapper::GetRemoteSSLCertificate() const {
   if (!dtls_) {
     return nullptr;
   }
@@ skipping 406 matching lines @@
                                      last_sent_packet_id, ready_to_send);
 }
 
 void DtlsTransportChannelWrapper::OnChannelStateChanged(
     TransportChannelImpl* channel) {
   ASSERT(channel == channel_);
   SignalStateChanged(this);
 }
 
 void DtlsTransportChannelWrapper::Reconnect() {
   set_dtls_state(DTLS_TRANSPORT_NEW);

[pthatcher1, 2016/07/13 00:04:19]

Maybe have a DCHECK(dtls_active_);

[Taylor Brandstetter, 2016/07/13 16:17:41]

No longer necessary. This is inlined in SetRemoteFingerprint which explicitly
checks dtls_active_.

   set_writable(false);
-  if (channel_->writable()) {
-    OnWritableState(channel_);
-  }
+  VERIFY(MaybeStartDtls());

[pthatcher1, 2016/07/13 00:04:19]

Can we inline this?

[Taylor Brandstetter, 2016/07/13 16:17:41]

Done.

 }
 
 }  // namespace cricket