Add performance tracing event to VideoCaptureDeviceAndroid::OnFrameAvailable

Add performance tracing event to VideoCaptureDeviceAndroid::OnFrameAvailable

BUG=329505
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=245531

[mcasas, 2013-12-18 13:21:17]

tommi@: mini patch, PTAL

wjia@: FYI.

[tommi (sloooow) - chröme, 2013-12-18 14:01:33]

https://codereview.chromium.org/98773003/diff/1/media/video/capture/android/v...
File media/video/capture/android/video_capture_device_android.cc (right):

https://codereview.chromium.org/98773003/diff/1/media/video/capture/android/v...
media/video/capture/android/video_capture_device_android.cc:200:
TRACE_EVENT0("video", "VideoCaptureDeviceAndroid::OnFrameAvailable");
Since Android is very sensitive to performance I have to ask... is there a
performance impact of doing this?
Will we change the outcome by measuring it?

[mcasas, 2013-12-18 14:32:36]

https://codereview.chromium.org/98773003/diff/1/media/video/capture/android/v...
File media/video/capture/android/video_capture_device_android.cc (right):

https://codereview.chromium.org/98773003/diff/1/media/video/capture/android/v...
media/video/capture/android/video_capture_device_android.cc:200:
TRACE_EVENT0("video", "VideoCaptureDeviceAndroid::OnFrameAvailable");
Well, nothing comes for free. From the docs:

"
Trace macros are very low overhead. When tracing is 
not turned on, trace macros cost at most a few dozen
clocks. When running, trace macros cost a few thousand 
clocks at most. Arguments to the trace macro are 
evaluated only when tracing is on --- if tracing is 
off, the value of the arguments dont get computed.
"

Consider wrapping around a #if !defined(NDEBUG) ?

[tommi (sloooow) - chröme, 2013-12-18 15:14:32]

lgtm

https://codereview.chromium.org/98773003/diff/1/media/video/capture/android/v...
File media/video/capture/android/video_capture_device_android.cc (right):

https://codereview.chromium.org/98773003/diff/1/media/video/capture/android/v...
media/video/capture/android/video_capture_device_android.cc:200:
TRACE_EVENT0("video", "VideoCaptureDeviceAndroid::OnFrameAvailable");
On 2013/12/18 14:32:36, mcasas wrote:
> Well, nothing comes for free. From the docs:
> 
> "
> Trace macros are very low overhead. When tracing is 
> not turned on, trace macros cost at most a few dozen
> clocks. When running, trace macros cost a few thousand 
> clocks at most. Arguments to the trace macro are 
> evaluated only when tracing is on --- if tracing is 
> off, the value of the arguments dont get computed.
> "
> 
> Consider wrapping around a #if !defined(NDEBUG) ?

That's good enough for me.  I know how this is implemented on other platforms
but don't know how it's done on Android.  Given the documentation this sounds
like an expected use case.

[commit-bot: I haz the power, 2014-01-16 16:28:32]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/mcasas@chromium.org/98773003/1

[commit-bot: I haz the power, 2014-01-16 19:36:41]

Retried try job too often on win_rel for step(s) browser_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_rel&nu...

[commit-bot: I haz the power, 2014-01-17 12:56:04]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/mcasas@chromium.org/98773003/1

[commit-bot: I haz the power, 2014-01-17 16:58:37]

Change committed as 245531