Add UMA stats for received frames or not in video track adapter.

Add UMA stats for received frames or not in video track adapter.

The adapter is torn down when a session is ended (no more tracks connected to it), so we do the logging in the destructor.

BUG=399835
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=289939

[mcasas, 2014-08-14 15:49:56]

lgtm

[mcasas, 2014-08-14 15:49:57]

lgtm

[Alexei Svitkine (slow), 2014-08-14 15:56:11]

https://codereview.chromium.org/466333005/diff/1/tools/metrics/histograms/his...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/466333005/diff/1/tools/metrics/histograms/his...
tools/metrics/histograms/histograms.xml:11444: +<histogram
name="Media.VideoTrackAdapter.FramesReceived" enum="Boolean">
Can you use a more specific enum? e.g. BooleanReceived (create it if it doesn't
exist yet)

https://codereview.chromium.org/466333005/diff/1/tools/metrics/histograms/his...
tools/metrics/histograms/histograms.xml:11447: +  <summary>If we received at
least one frame during a session or not.</summary>
Please clarify what "session" means, since that term can be overloaded. While
doing so, also mention when/how often this is recorded.

[Henrik Grunell, 2014-08-14 21:23:32]

Code review fixes.

Miguel: I can't see any stats registered. Can you take a look tomorrow (Friday)
and fix the CL if needed? When exactly is the video source destroyed? (And the
adapter with it.)

https://codereview.chromium.org/466333005/diff/1/tools/metrics/histograms/his...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/466333005/diff/1/tools/metrics/histograms/his...
tools/metrics/histograms/histograms.xml:11444: +<histogram
name="Media.VideoTrackAdapter.FramesReceived" enum="Boolean">
On 2014/08/14 15:56:10, Alexei Svitkine wrote:
> Can you use a more specific enum? e.g. BooleanReceived (create it if it
doesn't
> exist yet)

Done.

https://codereview.chromium.org/466333005/diff/1/tools/metrics/histograms/his...
tools/metrics/histograms/histograms.xml:11447: +  <summary>If we received at
least one frame during a session or not.</summary>
On 2014/08/14 15:56:11, Alexei Svitkine wrote:
> Please clarify what "session" means, since that term can be overloaded. While
> doing so, also mention when/how often this is recorded.

Done.

[Alexei Svitkine (slow), 2014-08-14 21:27:33]

lgtm

[tommi (sloooow) - chröme, 2014-08-15 13:50:48]

lgtm

[Henrik Grunell, 2014-08-15 14:02:43]

The CQ bit was checked by grunell@chromium.org

[commit-bot: I haz the power, 2014-08-15 14:04:25]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/grunell@chromium.org/466333005/20001

[commit-bot: I haz the power, 2014-08-15 18:17:34]

Committed patchset #2 (20001) as 289939