DevTools: fix concurrency problems in DevToolsFrameTraceRecorder

DevTools: fix concurrency problems in DevToolsFrameTraceRecorder

DevToolsFrameTraceRecorder used to mutate the class being traced
after the moment when it was traced, which created potential races
against conversion of that class to trace format, potentially performed
on a different thread after trace completion. Let's create a
retrospective trace event when frame capture is done instead. Also,
convert the trace event from instant to object snapshot, which is
more appropriate for the data being logged.

Tracing: add TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID_AND_TIMESTAMP()

BUG=

Committed: https://crrev.com/42d6d7e559bb9d85487dc27ac88ae3dc3e4e2544
Cr-Commit-Position: refs/heads/master@{#335886}

[caseq, 2015-06-16 14:36:18]

caseq@chromium.org changed reviewers:
+ dgozman@chromium.org, dsinclair@chromium.org, pfeldman@chromium.org

[dgozman, 2015-06-16 15:19:28]

devtools lgtm

https://codereview.chromium.org/1188773005/diff/1/content/browser/devtools/de...
File content/browser/devtools/devtools_frame_trace_recorder.cc (right):

https://codereview.chromium.org/1188773005/diff/1/content/browser/devtools/de...
content/browser/devtools/devtools_frame_trace_recorder.cc:85:
TRACE_DISABLED_BY_DEFAULT("devtools.screenshot"), "Screenshot", 1,
What are these "Screenshot" and 1?

https://codereview.chromium.org/1188773005/diff/1/content/browser/devtools/de...
content/browser/devtools/devtools_frame_trace_recorder.cc:139:
pending_frame_data_ = new DevToolsFrameTraceRecorderData(frame_metadata);
Let's delete this object once category or tracing is disabled.

[caseq, 2015-06-16 17:54:45]

On 2015/06/16 15:19:28, dgozman wrote:

>
https://codereview.chromium.org/1188773005/diff/1/content/browser/devtools/de...
> File content/browser/devtools/devtools_frame_trace_recorder.cc (right):
> 
>
https://codereview.chromium.org/1188773005/diff/1/content/browser/devtools/de...
> content/browser/devtools/devtools_frame_trace_recorder.cc:85:
> TRACE_DISABLED_BY_DEFAULT("devtools.screenshot"), "Screenshot", 1,
> What are these "Screenshot" and 1?

Event name and dummy object id. We generally don't extract these to constants
elsewhere.

>
https://codereview.chromium.org/1188773005/diff/1/content/browser/devtools/de...
> content/browser/devtools/devtools_frame_trace_recorder.cc:139:
> pending_frame_data_ = new DevToolsFrameTraceRecorderData(frame_metadata);
> Let's delete this object once category or tracing is disabled.

Done.

Dan, please take a look at trace_event/ part.

[dsinclair, 2015-06-16 19:44:51]

The CQ bit was checked by dsinclair@chromium.org

[dsinclair, 2015-06-16 19:44:52]

lgtm

[dsinclair, 2015-06-16 19:44:52]

The patchset sent to the CQ was uploaded after l-g-t-m from dgozman@chromium.org
Link to the patchset: https://codereview.chromium.org/1188773005/#ps20001
(title: "review comments addressed")

[commit-bot: I haz the power, 2015-06-16 19:46:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1188773005/20001

[caseq, 2015-06-16 20:29:21]

The CQ bit was unchecked by caseq@chromium.org

[caseq, 2015-06-16 20:32:21]

This depends on a front end change (https://codereview.chromium.org/1184383002/)
due to event type & name change.

[caseq, 2015-06-23 16:22:06]

The CQ bit was checked by caseq@chromium.org

[commit-bot: I haz the power, 2015-06-23 16:24:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1188773005/20001

[commit-bot: I haz the power, 2015-06-23 16:51:02]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-06-23 16:51:03]

Try jobs failed on following builders:
  chromeos_daisy_chromium_compile_only_ng on tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromeos_daisy_...)

[caseq, 2015-06-23 16:52:04]

The CQ bit was checked by caseq@chromium.org

[commit-bot: I haz the power, 2015-06-23 16:53:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1188773005/20001

[commit-bot: I haz the power, 2015-06-23 17:08:58]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-06-23 17:08:59]

Try jobs failed on following builders:
  cast_shell_linux on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/cast_shell_linu...)

[caseq, 2015-06-24 07:50:23]

The CQ bit was checked by caseq@chromium.org

[commit-bot: I haz the power, 2015-06-24 07:50:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1188773005/20001

[commit-bot: I haz the power, 2015-06-24 08:23:56]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-06-24 08:24:52]

Patchset 2 (id:??) landed as
https://crrev.com/42d6d7e559bb9d85487dc27ac88ae3dc3e4e2544
Cr-Commit-Position: refs/heads/master@{#335886}