QUIC/cronet - Fix crash bug b/28676259. Handle session_ being a nullptr.

net/quic/quic_http_stream.cc

 // Copyright (c) 2012 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 "net/quic/quic_http_stream.h"
 
 #include "base/callback_helpers.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/string_split.h"
 #include "base/strings/stringprintf.h"
@@ skipping 157 matching lines @@
 
   next_state_ = STATE_REQUEST_STREAM;
   int rv = DoLoop(OK);
   if (rv == ERR_IO_PENDING)
     callback_ = callback;
 
   return rv;
 }
 
 int QuicHttpStream::DoStreamRequest() {
+  if (session_.get() == nullptr) {

[xunjieli, 2016/06/07 23:46:25]

Could just do "if (!session_)". It's more consistent with the other null checks
in this file.  

[ramant (doing other things), 2016/06/07 23:58:32]

Regarding WeakPtr, the following discussion could be interesting.

https://mail.google.com/mail/u/0/#search/label%3Achromium-dev+weakptr/155189b...

Wanted to see if there is a platform specific bug. Will change it to (!session_)
and will add UMA histograms to track how many times we hit this condition.

[ramant (doing other things), 2016/06/18 00:18:05]

Uploaded CL: https://codereview.chromium.org/2073323003/ to collect histogram
data.

+    // TODO(rtenneti) Bug: b/28676259 - a temporary fix until we find out why
+    // |session_| could be a nullptr.
+    return was_handshake_confirmed_ ? ERR_CONNECTION_CLOSED
+                                    : ERR_QUIC_HANDSHAKE_FAILED;
+  }
   int rv = stream_request_.StartRequest(
       session_, &stream_,
       base::Bind(&QuicHttpStream::OnStreamReady, weak_factory_.GetWeakPtr()));
   if (rv == OK) {
     stream_->SetDelegate(this);
     if (request_info_->load_flags & LOAD_DISABLE_CONNECTION_MIGRATION) {
       stream_->DisableConnectionMigration();
     }
     if (response_info_) {
       next_state_ = STATE_SET_REQUEST_PRIORITY;
@@ skipping 584 matching lines @@
   closed_stream_sent_bytes_ = stream_->stream_bytes_written();
   stream_ = nullptr;
 
   // If |request_body_stream_| is non-NULL, Reset it, to abort any in progress
   // read.
   if (request_body_stream_)
     request_body_stream_->Reset();
 }
 
 }  // namespace net