Add comments for struct members that were changed from size_t to uin32_t or uint64_t for IPC safety.

media/cast/net/pacing/paced_sender.cc

 // Copyright 2014 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 "media/cast/net/pacing/paced_sender.h"
 
 #include "base/big_endian.h"
 #include "base/bind.h"
 #include "base/debug/dump_without_crashing.h"
 #include "base/message_loop/message_loop.h"
+#include "base/numerics/safe_conversions.h"
 
 namespace media {
 namespace cast {
 
 namespace {
 
 static const int64_t kPacingIntervalMs = 10;
 // Each frame will be split into no more than kPacingMaxBurstsPerFrame
 // bursts of packets.
 static const size_t kPacingMaxBurstsPerFrame = 3;
@@ skipping 326 matching lines @@
     event.rtp_timestamp = last_logged_video_rtp_timestamp_ =
         last_logged_video_rtp_timestamp_.Expand(truncated_rtp_timestamp);
     event.media_type = VIDEO_EVENT;
   } else {
     DVLOG(3) << "Got unknown ssrc " << ssrc << " when logging packet event";
     return;
   }
   success &= reader.Skip(2);
   success &= reader.ReadU16(&event.packet_id);
   success &= reader.ReadU16(&event.max_packet_id);
-  event.size = packet.size();
+  event.size = base::checked_cast<uint32_t>(packet.size());
   DCHECK(success);
 }
 
 }  // namespace cast
 }  // namespace media