Fix "value possibly truncated" warnings on MSVC, net/base edition.

net/base/network_change_notifier.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/base/network_change_notifier.h"
 
 #include <limits>
 
 #include "base/metrics/histogram.h"
 #include "base/synchronization/lock.h"
@@ skipping 287 matching lines @@
       fastest_RTT_since_last_connection_change_ = request_duration;
     }
     bytes_read_since_last_connection_change_ += bytes_read;
     if (request_duration < fastest_RTT_since_last_connection_change_)
       fastest_RTT_since_last_connection_change_ = request_duration;
     // Ignore tiny transfers which will not produce accurate rates.
     // Ignore zero duration transfers which might cause divide by zero.
     if (bytes_read > 10000 &&
         request_duration > base::TimeDelta::FromMilliseconds(1) &&
         request.creation_time() > last_connection_change_) {
-      int32 kbps = bytes_read * 8 / request_duration.InMilliseconds();
+      int32 kbps = static_cast<int32>(
+          bytes_read * 8 / request_duration.InMilliseconds());
       if (kbps > peak_kbps_since_last_connection_change_)
         peak_kbps_since_last_connection_change_ = kbps;
     }
 
     if (last_connection_type_ != NetworkChangeNotifier::CONNECTION_NONE)
       return;
 
     UMA_HISTOGRAM_MEDIUM_TIMES("NCN.OfflineDataRecv",
                                now - last_connection_change_);
     offline_packets_received_++;
@@ skipping 531 matching lines @@
   DCHECK(g_network_change_notifier);
   g_network_change_notifier = NULL;
 }
 
 NetworkChangeNotifier::DisableForTest::~DisableForTest() {
   DCHECK(!g_network_change_notifier);
   g_network_change_notifier = network_change_notifier_;
 }
 
 }  // namespace net