Encrypted Media: Add TRACE_EVENT to trace eme implementation performance.

Encrypted Media: Add TRACE_EVENT to trace eme implementation performance.

This CL adds TRACE_EVENT for video decrypt-and-decode path only. If needed, we could do the same for decrypt-only and/or audio.

TBR=dmichael@chromium.org
BUG=158981
TEST=goto chrome://tracing, record/stop, choose only "eme" in "Category", and enjoy.


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=165625

[xhwang, 2012-11-01 19:34:46]

PTAL!

[scherkus (not reviewing), 2012-11-01 22:22:36]

lgtm w/ q + nit

cool stuff!

http://codereview.chromium.org/11360042/diff/1/media/filters/decrypting_video...
File media/filters/decrypting_video_decoder.cc (right):

http://codereview.chromium.org/11360042/diff/1/media/filters/decrypting_video...
media/filters/decrypting_video_decoder.cc:296: "eme",
"DecryptingVideoDecoder::DecodePendingBuffer", ++trace_id_);
OOC does ++trace_id_ still execute if we're not tracing?

http://codereview.chromium.org/11360042/diff/1/media/filters/decrypting_video...
File media/filters/decrypting_video_decoder.h (right):

http://codereview.chromium.org/11360042/diff/1/media/filters/decrypting_video...
media/filters/decrypting_video_decoder.h:160: unsigned int trace_id_;
do we need unsigned?

[xhwang, 2012-11-02 01:33:54]

http://codereview.chromium.org/11360042/diff/1/media/filters/decrypting_video...
File media/filters/decrypting_video_decoder.cc (right):

http://codereview.chromium.org/11360042/diff/1/media/filters/decrypting_video...
media/filters/decrypting_video_decoder.cc:296: "eme",
"DecryptingVideoDecoder::DecodePendingBuffer", ++trace_id_);
On 2012/11/01 22:22:36, scherkus wrote:
> OOC does ++trace_id_ still execute if we're not tracing?

Good question. Experiments show that when not recording, the trace_id is not
incremented.

http://codereview.chromium.org/11360042/diff/1/media/filters/decrypting_video...
File media/filters/decrypting_video_decoder.h (right):

http://codereview.chromium.org/11360042/diff/1/media/filters/decrypting_video...
media/filters/decrypting_video_decoder.h:160: unsigned int trace_id_;
On 2012/11/01 22:22:36, scherkus wrote:
> do we need unsigned?

I am super paranoid, about what if the trace_id_ overflows.  Overflowing "int"
is undefined behavior. "unsigned" gives me peace of mind.

[commit-bot: I haz the power, 2012-11-02 01:34:12]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/xhwang@chromium.org/11360042/1

[commit-bot: I haz the power, 2012-11-02 01:34:16]

Presubmit check for 11360042-1 failed and returned exit status 1.


Running presubmit commit checks ...

** Presubmit ERRORS **
Missing LGTM from an OWNER for files in these directories:
    webkit/plugins/ppapi

[commit-bot: I haz the power, 2012-11-02 01:38:49]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/xhwang@chromium.org/11360042/4002

[commit-bot: I haz the power, 2012-11-02 05:32:26]

Change committed as 165625