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

media/cast/sender/rtp_timestamp_helper.cc

Index: media/cast/sender/rtp_timestamp_helper.cc
diff --git a/media/cast/sender/rtp_timestamp_helper.cc b/media/cast/sender/rtp_timestamp_helper.cc
index ea0c35c66fbf130d3b41d55b69eb4930b0d4bcbf..9314af258bd3056cb41d4b844e79b2de4b2705fc 100644
--- a/media/cast/sender/rtp_timestamp_helper.cc
+++ b/media/cast/sender/rtp_timestamp_helper.cc
@@ -4,6 +4,8 @@
 
 #include "media/cast/sender/rtp_timestamp_helper.h"
 
+#include "media/cast/cast_defines.h"
+
 namespace media {
 namespace cast {
 
@@ -15,13 +17,12 @@ RtpTimestampHelper::RtpTimestampHelper(int frequency)
 RtpTimestampHelper::~RtpTimestampHelper() {
 }
 
-bool RtpTimestampHelper::GetCurrentTimeAsRtpTimestamp(
-    const base::TimeTicks& now, uint32* rtp_timestamp) const {
+bool RtpTimestampHelper::EstimateRtpTimestamp(
+    const base::TimeTicks& t, uint32* rtp_timestamp) const {
   if (last_capture_time_.is_null())
     return false;
-  const base::TimeDelta elapsed_time = now - last_capture_time_;
-  const int64 rtp_delta =
-      elapsed_time * frequency_ / base::TimeDelta::FromSeconds(1);
+  const base::TimeDelta elapsed_time = t - last_capture_time_;
+  const int64 rtp_delta = TimeDeltaToRtpDelta(elapsed_time, frequency_);
   *rtp_timestamp = last_rtp_timestamp_ + static_cast<uint32>(rtp_delta);
   return true;
 }