Revert of "Revert 'QUIC - check for null stream_ before calling stream_'s IsDoneReading'"

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 690 matching lines @@
   response_info_->npn_negotiated_protocol = "quic/1+spdy/3";
   response_info_->response_time = base::Time::Now();
   response_info_->request_time = request_time_;
   response_headers_received_ = true;
 
   return OK;
 }
 
 int QuicHttpStream::ReadAvailableData(IOBuffer* buf, int buf_len) {
   int rv = stream_->Read(buf, buf_len);
+  // TODO(rtenneti): Temporary fix for crbug.com/585591. Added a check for null
+  // |stream_| to fix crash bug. Delete |stream_| check and histogram after fix
+  // is merged.
+  bool null_stream = stream_ == nullptr;
+  UMA_HISTOGRAM_BOOLEAN("Net.QuicReadAvailableData.NullStream", null_stream);
+  if (null_stream)
+    return rv;
   if (stream_->IsDoneReading()) {
     stream_->SetDelegate(nullptr);
     stream_->OnFinRead();
     ResetStream();
   }
   return rv;
 }
 
 void QuicHttpStream::ResetStream() {
   if (push_handle_) {
     push_handle_->Cancel();
     push_handle_ = nullptr;
   }
   if (!stream_)
     return;
   closed_stream_received_bytes_ = stream_->stream_bytes_read();
   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