[Cast] In Audio/VideoSender, drop frames when too-long a duration is in-flight.

media/cast/cast_defines.h

 // Copyright 2013 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.
 
 #ifndef MEDIA_CAST_CAST_DEFINES_H_
 #define MEDIA_CAST_CAST_DEFINES_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 177 matching lines @@
       ntp_time_us -
       (kUnixEpochInNtpSeconds * base::Time::kMicrosecondsPerSecond));
   return base::TimeTicks::UnixEpoch() + elapsed_since_unix_epoch;
 }
 
 inline base::TimeDelta RtpDeltaToTimeDelta(int64 rtp_delta, int rtp_timebase) {
   DCHECK_GT(rtp_timebase, 0);
   return rtp_delta * base::TimeDelta::FromSeconds(1) / rtp_timebase;
 }
 
+inline int64 TimeDeltaToRtpDelta(base::TimeDelta delta, int rtp_timebase) {
+  DCHECK_GT(rtp_timebase, 0);
+  return delta * rtp_timebase / base::TimeDelta::FromSeconds(1);
+}
+
 }  // namespace cast
 }  // namespace media
 
 #endif  // MEDIA_CAST_CAST_DEFINES_H_