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

net/quic/quic_http_stream.cc

Index: net/quic/quic_http_stream.cc
diff --git a/net/quic/quic_http_stream.cc b/net/quic/quic_http_stream.cc
index 0a006e2c1803cdf877ec27eaf1ded0a077c5c210..e733319dbb41545b9d40672af24644be815e4ec7 100644
--- a/net/quic/quic_http_stream.cc
+++ b/net/quic/quic_http_stream.cc
@@ -708,6 +708,13 @@ int QuicHttpStream::ProcessResponseHeaders(const SpdyHeaderBlock& headers) {
 
 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();