Log current time if we stop logging before stop_time_.

webrtc/call/rtc_event_log_helper_thread.cc

Index: webrtc/call/rtc_event_log_helper_thread.cc
diff --git a/webrtc/call/rtc_event_log_helper_thread.cc b/webrtc/call/rtc_event_log_helper_thread.cc
index b1b6990a2449862fb8dfe0e7cff54d1c4486859b..c0f89726311bbc1c983f43291327463289ec0e82 100644
--- a/webrtc/call/rtc_event_log_helper_thread.cc
+++ b/webrtc/call/rtc_event_log_helper_thread.cc
@@ -224,7 +224,11 @@ void RtcEventLogHelperThread::StopLogFile() {
   output_string_.clear();
 
   rtclog::Event end_event;
-  end_event.set_timestamp_us(stop_time_);
+  // This function can be called either because we have reached the stop time,
+  // or because we have reached the log file size limit. Therefore, use the
+  // current time if we have not reached the time limit.
+  end_event.set_timestamp_us(
+      std::min(stop_time_, clock_->TimeInMicroseconds()));

[ivoc, 2016/07/27 09:18:00]

Do you know if the value from TimeInMicroseconds() can wrap?

[pbos-webrtc, 2016/07/27 16:44:20]

This should never wrap. (It calls rtc::TimeMicros() which is ~64-bit sized, all
of our code relies on this not wrapping).

[terelius, 2016/07/27 20:34:40]

When I wrote the code, I assumed that the 64-bit time couldn't wrap. However,
after looking at it earlier today, I am not so sure.

On mac, rtc::TimeMicros() does
ticks = mach_absolute_time() * timebase.numer / timebase.denom;
where mach_absolute_time() measures (roughly) CPU cycles and timebase is a
fraction that scales the CPU cycles to nanoseconds. If the timebase is
1000000000/33333335 then the computation will wrap after about 10 minutes.

https://developer.apple.com/library/mac/qa/qa1398/_index.html also mentions that
there is a danger of overflowing. On the other hand, I've also read that the
timebase is 1/1 on Intel CPU so this would only be an issue on PowerPC.

If it does wrap on some platform, we're going to have bigger problems than just
an incorrect timestamp in a log, though.

   end_event.set_type(rtclog::Event::LOG_END);
   AppendEventToString(&end_event);