Telemetry: Fix frame counting on Mac

Telemetry: Fix timeline frame counting on Mac

We want to count the last the last swap in the embedding
chain. Usually there is a hardware swap for this but on mac
there doesn't appear to be one. This uses the decoder swap
for now until we know the canonical swap call and add a trace
there.

TBR=nduca@chromium.org
NOTRY=true

No-try since this is blocking this from working on the mac and I've run the tests locally.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=245478

[epenner, 2014-01-17 03:12:28]

Ptal.

If this doesn't fix the mac I'll likely need to run it locally. From looking at
mac traces it looks like there is no real surface used so we don't see 'real'
frames getting produced. This uses the decoder for now which will hopefully get
this running.

[commit-bot: I haz the power, 2014-01-17 03:17:25]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/epenner@chromium.org/141163004/50001

[commit-bot: I haz the power, 2014-01-17 04:09:56]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/epenner@chromium.org/141163004/90001

[nduca, 2014-01-17 04:26:05]

lgtm should we just use drawLayers on the compositor thread to indicate this? or
use the markers renderstats puts in?

[epenner, 2014-01-17 04:34:01]

On 2014/01/17 04:26:05, nduca wrote:
> lgtm should we just use drawLayers on the compositor thread to indicate this?
or
> use the markers renderstats puts in?

I kind of liked getting the very end of the fast path, but I suppose it's just a
bug if it's not 1-1.

Do render-stats always run when traces run? I'm just not familiar but that
sounds promising also.

[ernstm, 2014-01-17 06:10:21]

On 2014/01/17 04:34:01, epenner wrote:
> On 2014/01/17 04:26:05, nduca wrote:
> > lgtm should we just use drawLayers on the compositor thread to indicate
this?
> or
> > use the markers renderstats puts in?
> 
> I kind of liked getting the very end of the fast path, but I suppose it's just
a
> bug if it's not 1-1.
> 
> Do render-stats always run when traces run? I'm just not familiar but that
> sounds promising also.

The easiest way to record rendering stats is passing the
--enable-gpu-benchmarking command line flag and recording a trace with the
'benchmark' category enabled (smoothness measurement does that). You can then
extract the frame count from the trace by using
tools/perf/metrics/rendering_stats.py. The trace events issued by the rendering
stats mechanism are somewhat protected from event renaming by being in a source
file with per-file OWNER (cc/debug/benchmark_instrumentation.cc).

[commit-bot: I haz the power, 2014-01-17 10:10:12]

Change committed as 245478