Add histograms to track how long QUIC read/write operations take to complete.

net/quic/quic_client_session.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_client_session.h"
 
 #include "base/callback_helpers.h"
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/sparse_histogram.h"
@@ skipping 743 matching lines @@
 
 void QuicClientSession::StartReading() {
   if (read_pending_) {
     return;
   }
   read_pending_ = true;
   int rv = socket_->Read(read_buffer_.get(),
                          read_buffer_->size(),
                          base::Bind(&QuicClientSession::OnReadComplete,
                                     weak_factory_.GetWeakPtr()));
+  UMA_HISTOGRAM_BOOLEAN("Net.QuicSession.AsyncRead", rv == ERR_IO_PENDING);
   if (rv == ERR_IO_PENDING) {
     num_packets_read_ = 0;
     return;
   }
 
   if (++num_packets_read_ > 32) {
     num_packets_read_ = 0;
     // Data was read, process it.
     // Schedule the work through the message loop to 1) prevent infinite
     // recursion and 2) avoid blocking the thread for too long.
@@ skipping 158 matching lines @@
     return;
 
   // TODO(rch): re-enable this code once beta is cut.
   //  if (stream_factory_)
   //    stream_factory_->OnSessionConnectTimeout(this);
   //  CloseAllStreams(ERR_QUIC_HANDSHAKE_FAILED);
   //  DCHECK_EQ(0u, GetNumOpenStreams());
 }
 
 }  // namespace net