Redo TimelineTask API

Redo TimelineTask API

A TimelineTask represents an asynchronous track of operations on the timeline.

The old API allowed multiple isolates to emit events simultaneously on the same task or to start / finish events in any order. This isn't supported by our UI and probably many other tools that consume trace-event.

With this change, operations within a TimelineTask must complete in the reverse order of their start calls (aka a stack). You can pass a TimelineTask from one isolate to another but you must first complete all open operations before passing it.

Example:

var task = new TimelineTask();

task.start('Some phase');
await someFuture;
task.finish();


Also: Add support for instant events.

R=rmacnak@google.com

Committed: https://github.com/dart-lang/sdk/commit/291befa1cdb6c141fc24a0edaa048c41d69ada72

[Cutch, 2015-11-10 20:32:21]

Description was changed from

==========
Redo TimelineTask API
==========

to

==========
Redo TimelineTask API

A TimelineTask represents an asynchronous track of operations on the timeline. 

The old API allowed multiple isolates to emit events simultaneously on the same
task or to start / finish events in any order. This isn't supported by our UI
and probably many other tools that consume trace-event.

With this change, operations within a TimelineTask must complete in the reverse
order of their start calls (aka a stack). You can pass a TimelineTask from one
isolate to another but you must first complete all open operations before
passing it.

Example:

var task = new TimelineTask();

task.start('Some phase');
await someFuture;
task.finish();
==========

[Cutch, 2015-11-10 20:32:21]

johnmccutchan@google.com changed reviewers:
+ rmacnak@google.com

[Cutch, 2015-11-11 18:09:25]

Description was changed from

==========
Redo TimelineTask API

A TimelineTask represents an asynchronous track of operations on the timeline. 

The old API allowed multiple isolates to emit events simultaneously on the same
task or to start / finish events in any order. This isn't supported by our UI
and probably many other tools that consume trace-event.

With this change, operations within a TimelineTask must complete in the reverse
order of their start calls (aka a stack). You can pass a TimelineTask from one
isolate to another but you must first complete all open operations before
passing it.

Example:

var task = new TimelineTask();

task.start('Some phase');
await someFuture;
task.finish();
==========

to

==========
Redo TimelineTask API

A TimelineTask represents an asynchronous track of operations on the timeline. 

The old API allowed multiple isolates to emit events simultaneously on the same
task or to start / finish events in any order. This isn't supported by our UI
and probably many other tools that consume trace-event.

With this change, operations within a TimelineTask must complete in the reverse
order of their start calls (aka a stack). You can pass a TimelineTask from one
isolate to another but you must first complete all open operations before
passing it.

Example:

var task = new TimelineTask();

task.start('Some phase');
await someFuture;
task.finish();


Also: Add support for instant events.
==========

[Cutch, 2015-11-11 18:11:15]

PTAL

[rmacnak, 2015-11-11 18:23:09]

lgtm

[Cutch, 2015-11-11 18:59:43]

Committed patchset #4 (id:60001) manually as
291befa1cdb6c141fc24a0edaa048c41d69ada72 (presubmit successful).