[Cast] RTT clean-up to the max!

[Cast] RTT clean-up to the max!

Executing some very badly needed clean-up of code that handles passing
around round trip time measurements and managing stats.  This change
removes a lot of dead code, addresses TODOs for minor things that were
dependent on this clean-up, and enhances RTCP unit testing.

BUG=404813
Committed: https://crrev.com/d89ef69a19b9015bf503f5f5d68d163d2ecd05de
Cr-Commit-Position: refs/heads/master@{#293887}

[miu, 2014-09-04 02:01:35]

miu@chromium.org changed reviewers:
+ hubbe@chromium.org, kenrb@chromium.org

[miu, 2014-09-04 02:01:35]

hubbe: PTAL at everything.

kenrb: Need OWNERS stamp for chrome/common/cast_messages.h.

[kenrb, 2014-09-04 19:36:35]

ipc lgtm

[hubbe, 2014-09-04 22:51:27]

https://codereview.chromium.org/532373003/diff/1/media/cast/net/rtcp/rtcp.cc
File media/cast/net/rtcp/rtcp.cc (right):

https://codereview.chromium.org/532373003/diff/1/media/cast/net/rtcp/rtcp.cc#...
media/cast/net/rtcp/rtcp.cc:268: // Logically, the minimum offset between the
clocks has to be the correct
This logic doesn't apply if you subtract half the round-trip time above.

[miu, 2014-09-05 18:29:40]

https://codereview.chromium.org/532373003/diff/1/media/cast/net/rtcp/rtcp.cc
File media/cast/net/rtcp/rtcp.cc (right):

https://codereview.chromium.org/532373003/diff/1/media/cast/net/rtcp/rtcp.cc#...
media/cast/net/rtcp/rtcp.cc:268: // Logically, the minimum offset between the
clocks has to be the correct
On 2014/09/04 22:51:27, hubbe wrote:
> This logic doesn't apply if you subtract half the round-trip time above.

I think it applies regardless, right?  Meaning, the RTT measurement could be
erroneous, but a low RTT measurement would provide a more-accurate clock offset
estimate.

As it stands, since the sender doesn't send the delay report block anymore, the
|current_round_trip_time_| is always zero, so this change has no effect for now.

If I'm missing something major here, I could put back the old LOC (with the TODO
comment), and address this in a later change...

[miu, 2014-09-05 20:54:38]

https://codereview.chromium.org/532373003/diff/1/media/cast/net/rtcp/rtcp.cc
File media/cast/net/rtcp/rtcp.cc (right):

https://codereview.chromium.org/532373003/diff/1/media/cast/net/rtcp/rtcp.cc#...
media/cast/net/rtcp/rtcp.cc:268: // Logically, the minimum offset between the
clocks has to be the correct
On 2014/09/05 18:29:40, miu wrote:
> If I'm missing something major here, I could put back the old LOC (with the
TODO
> comment), and address this in a later change...

Reverted these LOC, as discussed.

[hubbe, 2014-09-05 21:10:28]

lgtm

[miu, 2014-09-08 23:57:15]

The CQ bit was checked by miu@chromium.org

[commit-bot: I haz the power, 2014-09-09 00:28:47]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/miu@chromium.org/532373003/60001

[miu, 2014-09-09 03:53:36]

The CQ bit was unchecked by miu@chromium.org

[miu, 2014-09-09 03:54:23]

The CQ bit was checked by miu@chromium.org

[commit-bot: I haz the power, 2014-09-09 04:11:14]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/miu@chromium.org/532373003/60001

[commit-bot: I haz the power, 2014-09-09 07:37:06]

Committed patchset #4 (id:60001) as 5227057e77f51fc6a8882130e7d441adf88f98ec

[commit-bot: I haz the power, 2014-09-10 03:51:43]

Patchset 4 (id:??) landed as
https://crrev.com/d89ef69a19b9015bf503f5f5d68d163d2ecd05de
Cr-Commit-Position: refs/heads/master@{#293887}