Add new video metrics from webrtc to histograms.xml.

Add new video metrics from webrtc to histograms.xml.

- number of sent/received RTCP NACK/FIR/PLI per minute
- percentage of unique sent/received NACK requests
- percentage of discarded/duplicated packets by the jitter buffer
- permille of sent/received key frames

CL where stats will be added:
https://webrtc-codereview.appspot.com/24959004/

BUG=419657
Committed: https://crrev.com/f3684a08bda8522afff4267fdfc2ceb8705e9980
Cr-Commit-Position: refs/heads/master@{#302601}

[asapersson2, 2014-10-29 11:25:59]

asapersson@chromium.org changed reviewers:
+ mflodman@chromium.org

[asapersson2, 2014-10-29 18:01:12]

Patchset #1 (id:1) has been deleted

[asapersson2, 2014-10-30 10:38:06]

Patchset #1 (id:20001) has been deleted

[asapersson2, 2014-10-30 11:06:16]

asapersson@chromium.org changed reviewers:
+ asvitkine@chromium.org

[asapersson2, 2014-10-30 11:13:54]

Please take a look.

[mflodman_chromium_OOO, 2014-10-31 08:00:02]

LGTM, but it would be good create a crbug track WebRTC video stats we're about
to land the coming weeks and add here or link to a WebRTC bug.

[asapersson2, 2014-10-31 08:21:48]

On 2014/10/31 08:00:02, mflodman wrote:
> LGTM, but it would be good create a crbug track WebRTC video stats we're about
> to land the coming weeks and add here or link to a WebRTC bug.

Done.

[Alexei Svitkine (slow), 2014-10-31 16:55:25]

https://codereview.chromium.org/687203002/diff/40001/tools/metrics/histograms...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/687203002/diff/40001/tools/metrics/histograms...
tools/metrics/histograms/histograms.xml:39116: +  <summary>The number of
received RTCP FIR packets per minute.</summary>
When is this recorded? Every minute? Only when a video is playing?

https://codereview.chromium.org/687203002/diff/40001/tools/metrics/histograms...
tools/metrics/histograms/histograms.xml:39126: +  <summary>Permille of received
frames that are key frames.</summary>
Again when is this recorded? At the end of session? Multiple times during a
session, so you get double counting? Please make all of these descriptions more
precise so it's clearer what and how they are measuring things.

https://codereview.chromium.org/687203002/diff/40001/tools/metrics/histograms...
tools/metrics/histograms/histograms.xml:39163: +  <summary>Percentage of sent
NACKed RTP packets that are unique.</summary>
When is this recorded? Please document.

[asapersson2, 2014-11-03 10:01:04]

https://codereview.chromium.org/687203002/diff/40001/tools/metrics/histograms...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/687203002/diff/40001/tools/metrics/histograms...
tools/metrics/histograms/histograms.xml:39116: +  <summary>The number of
received RTCP FIR packets per minute.</summary>
On 2014/10/31 16:55:24, Alexei Svitkine wrote:
> When is this recorded? Every minute? Only when a video is playing?

Done.

https://codereview.chromium.org/687203002/diff/40001/tools/metrics/histograms...
tools/metrics/histograms/histograms.xml:39126: +  <summary>Permille of received
frames that are key frames.</summary>
On 2014/10/31 16:55:24, Alexei Svitkine wrote:
> Again when is this recorded? At the end of session? Multiple times during a
> session, so you get double counting? Please make all of these descriptions
more
> precise so it's clearer what and how they are measuring things.

Updated comments and added when metrics are recorded.

https://codereview.chromium.org/687203002/diff/40001/tools/metrics/histograms...
tools/metrics/histograms/histograms.xml:39163: +  <summary>Percentage of sent
NACKed RTP packets that are unique.</summary>
On 2014/10/31 16:55:24, Alexei Svitkine wrote:
> When is this recorded? Please document.

Done.

[Alexei Svitkine (slow), 2014-11-03 15:15:03]

lgtm

[asapersson2, 2014-11-04 09:45:59]

The CQ bit was checked by asapersson@chromium.org

[commit-bot: I haz the power, 2014-11-04 09:46:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/687203002/80001

[commit-bot: I haz the power, 2014-11-04 11:51:21]

Committed patchset #3 (id:80001)

[commit-bot: I haz the power, 2014-11-04 11:51:57]

Patchset 3 (id:??) landed as
https://crrev.com/f3684a08bda8522afff4267fdfc2ceb8705e9980
Cr-Commit-Position: refs/heads/master@{#302601}